1) The document discusses Oracle ASM Filter Driver (ASMFD), ASMLIB, and how they relate to managing I/O for Oracle databases on Linux. ASMFD replaces ASMLIB, providing persistent device naming and preventing accidental overwrites of Oracle disks.
2) It provides information on when and how to use ASM with and without ASMLIB, alternatives to each, and how to configure Oracle single-instance and RAC databases with and without ASM and ASMLIB. Configuration without these components can use filesystems, LVM, or third-party cluster file systems instead.
Nabil Nawaz Oracle Oracle 12c Data Guard Deep Dive PresentationNabil Nawaz
This document provides an overview of Oracle Dataguard including:
- Dataguard allows configuration of up to 30 physical or logical standby databases for high availability and disaster recovery.
- It provides benefits such as offloading backups and reporting without impacting primary database performance.
- Key concepts include primary and standby databases, redo transport, and different protection modes for data replication.
"Extended" or "Stretched" Oracle RAC has been available as a concept for a while. Oracle RAC 12c Release 2 introduces an Oracle Extended Cluster configuration, in which the cluster understands the concept of sites and extended setups. This knowledge is used to more efficiently manage "Extended Oracle RAC", whether the nodes are 0.1 mile or 10 miles apart.
The presentation was last updated on August 7th 2017 to add a reference to the new MAA White Paper: "Installing Oracle Extended Clusters on Exadata Database Machine" - http://www.oracle.com/technetwork/database/availability/maa-extclusters-installguide-3748227.pdf and to correct some minor details.
Understanding oracle rac internals part 2 - slidesMohamed Farouk
This document discusses Oracle Real Application Clusters (RAC) internals, specifically focusing on client connectivity and node membership. It provides details on how clients connect to a RAC database, including connect time load balancing, connect time and runtime connection failover. It also describes the key processes that manage node membership in Oracle Clusterware, including CSSD and how it uses network heartbeats and voting disks to monitor nodes and remove failed nodes from the cluster.
The document discusses different types of MySQL replication including asynchronous, semi-synchronous, and synchronous. It provides pros and cons of each type and describes how they handle transaction ordering, parallelism, flow control, and consistency. The key points are that asynchronous replication has potential for data loss and stale reads, semi-synchronous reduces but does not eliminate data loss risk, while SchoonerSQL's synchronous replication guarantees no data loss and failover without stalled transactions.
DB Time, Average Active Sessions, and ASH Math - Oracle performance fundamentalsJohn Beresniewicz
RMOUG 2020 abstract:
This session will cover core concepts for Oracle performance analysis first introduced in Oracle 10g and forming the backbone of many features in the Diagnostic and Tuning packs. The presentation will cover the theoretical basis and meaning of these concepts, as well as illustrate how they are fundamental to many user-facing features in both the database itself and Enterprise Manager.
This document summarizes a presentation on Oracle RAC (Real Application Clusters) internals with a focus on Cache Fusion. The presentation covers:
1. An overview of Cache Fusion and how it allows data to be shared across instances to enable scalability.
2. Dynamic re-mastering which adjusts where data is mastered based on access patterns to reduce messaging.
3. Techniques for handling contention including partitioning, connection pools, and separating redo logs.
4. Benefits of combining Oracle Multitenant and RAC such as aligning PDBs to instances.
5. How Oracle In-Memory Column Store fully integrates with RAC including fault tolerance features.
Adapting and adopting SQL Plan Management (SPM) to achieve execution plan stability for sub-second queries on a high-rate OLTP mission-critical application
Cluster Health Advisor (CHA) Deep Dive by Mark ScardinaMarkus Michalewicz
Oracle Database 12c Rel. 2Cluster Health Advisor Deep Dive- How it Works and How to Use It by Mark Scardina. CHA is an elementary part of Oracle's new Autonomous Health Framework (AHF). CHA provides real time monitoring of Oracle RAC database systems and their hosts for early detection of impending as well as ongoing system faults as well as diagnoses and identification of the most likely root causes.
PostgreSQL comes built-in with a variety of indexes, some of which are further extensible to build powerful new indexing schemes. But what are all these index types? What are some of the special features of these indexes? What are the size & performance tradeoffs? How do I know which ones are appropriate for my application?
Fortunately, this talk aims to answer all of these questions as we explore the whole family of PostgreSQL indexes: B-tree, expression, GiST (of all flavors), GIN and how they are used in theory and practice.
Make Your Application “Oracle RAC Ready” & Test For ItMarkus Michalewicz
This presentation talks about the secrets behind Oracle RAC’s horizontal scaling algorithm, Cache Fusion, and how you can ensure that your application is “Oracle RAC ready.”. It discusses do's and don'ts and how to test your application for "Oracle RAC readiness". This version was first presented in Sangam19.
This document provides an overview of how to use various Oracle performance monitoring and diagnostic tools like ASH, AWR, and SQL Monitor to analyze and troubleshoot performance issues. It begins with introductions and background on the speaker. It then demonstrates how to generate and interpret reports from these tools using the Oracle Enterprise Manager console and command line. It provides examples of querying ASH data directly and using tools like Compare ADDM and SQL Monitor. The document aims to help users quickly understand performance problems by leveraging these built-in Oracle performance diagnostics.
Oracle ASM Training covers database and storage concepts, ASM architecture, installation and configuration of ASMLIB, creating and managing ASM disk groups, best practices for ASM configuration, and migrating databases to ASM. The document includes an agenda with topics on ASM, ASMLIB, disk groups, files, redundancy, rebalancing, and troubleshooting. It also lists office locations for consulting services.
Are your Oracle databases highly available? You have deployed Real Application Clusters (RAC), Data Guard, or Failover Clusters and are well protected against server failures? Great – the prerequisites for a highly available environment are given. However, to assure that backend infrastructure failures also remain transparent to the client, an appropriate configuration is a prerequisite.
This lecture will discuss the Oracle technologies that can be used to achieve automatic client failover functionality. What are the advantages, but also the limitations of these technologies?
Oracle Drivers configuration for High Availability, is it a developer's job?Ludovico Caldara
UCP, GridLink, TAF, AC, TAC, FAN… The configuration of Oracle Drivers for application high availability is not an easy job. The developers often care about the minimal working configuration, while the DBAs are busy with the operations. In this session I will try to demystify application server’s connectivity to the database and give a direction toward the highest availability, using Real Application Clusters and new Oracle features like TAC and CMAN TDM.
This document discusses Oracle Multitenant 19c and pluggable databases. It begins with an introduction to the speaker and overview of pluggable databases. It then describes the traditional Oracle database architecture and the multitenant architecture in Oracle 19c. It discusses the different components of a container database including the root, seed PDB, and application containers. It also covers how to create pluggable databases from scratch, through cloning locally and remotely, relocating PDBs, and plugging in unplugged PDBs.
This document describes how to enable Oracle Database Vault 11gR2. It outlines the software and environment needed, including Oracle Database 11.2.0.4. It provides steps to enable the Database Vault option using SQL commands and the Database Configuration Assistant. These include shutting down the database, making changes to enable certain options, and configuring Database Vault using the DBCA interface. Once complete, the Database Vault configuration screens can be accessed.
The Top 5 Reasons to Deploy Your Applications on Oracle RACMarkus Michalewicz
This document discusses the top 5 reasons to deploy applications on Oracle Real Application Clusters (RAC). It discusses how RAC provides:
1. Developer productivity through transparency that allows developers to focus on application code without worrying about high availability or scalability.
2. Integrated scalability for both applications and database features through techniques like parallel execution and cache fusion that allow linear scaling.
3. Seamless high availability for the entire application stack through capabilities like fast reconfiguration times and zero data loss that prevent application outages.
4. Isolated consolidation for converged use cases through features like pluggable database isolation that allow secure sharing of hardware resources.
5. Full flexibility to choose deployment options
What's New and Coming in Oracle ASM 12c Rel. 2 - by Jim WilliamsMarkus Michalewicz
This document discusses new and upcoming features in Oracle Automatic Storage Management (ASM) and the Automatic Storage Management Cluster File System (ACFS). It begins with an overview of ASM and ACFS as the Oracle storage stack. The document then reviews the evolution of ASM and ACFS features over time, from basic storage management in earlier versions to expanded clustering and high availability in more recent releases. Finally, it outlines the agenda for the presentation, including what's new in ASM, new ACFS features, and reasons why an organization may not be using ASM.
Oracle Flex ASM - What’s New and Best Practices by Jim WilliamsMarkus Michalewicz
Oracle Open World (OOW) 2014 Presentation by Jim Williams (Oracle ASM Product Manager) on Oracle Flex ASM - What's New and Best Practices. The presentation provides an overview of enhancements (What's New) in Oracle ASM 12c, especially with respect to Oracle Flex ASM, and provides best practices which can be applied in any environment (Flex or Standard ASM). This presentation has also more background information for some of the configuration recommendations that I made in my "Oracle RAC (12.1.0.2) Operational Best Practices" presentation.
This document provides an overview of Oracle Automatic Storage Management (ASM). It describes ASM's architecture and components, including ASM instances, disk groups, disks, files, and utilities for managing ASM. Key benefits of ASM include striping files across disks for load balancing, mirroring for redundancy, and features like online disk reconfiguration and dynamic rebalancing.
This document provides an overview and configuration details for Oracle Flex Clusters and Flex ASM in Oracle Database 12c. Key points include:
- Flex Clusters introduce a hub-and-spoke topology that can scale to 64 hub nodes and many more leaf nodes to reduce interconnect complexity.
- Flex ASM allows database instances to connect to ASM instances running on a subset of nodes rather than each node, improving high availability.
- Configuring a Flex Cluster requires specifying hub and leaf nodes. Flex ASM is automatically enabled. Existing clusters can be converted to Flex mode.
- The architecture introduces an ASM network for communication between ASM and clients. ASM listeners provide load balancing across instances.
The document describes the limitations of the current Oracle architecture using single instance databases with DataGuard for high availability and discusses the benefits of a new resilient infrastructure using Oracle RAC and ASM. It provides an overview of the components in a demo system including the network, systems, software, storage and shared Oracle homes. It also discusses how NetApp filers can provide storage and snapshots, and how SMO manages consistency when using flex clones of databases.
Andrejs Karpovs presented on using ACFS as a storage solution for E-Business Suite applications. He discussed how ACFS works with ASM and the Oracle Cloud, provided demos of ACFS features like snapshots and replication, and explained that while not officially certified, many customers successfully use ACFS for EBS with no issues encountered. The presentation covered tips for managing ACFS and new features available in 12c like highly available NFS.
This document provides an overview and step-by-step instructions for installing and configuring Oracle VM 3.x. It discusses the hardware and software requirements for installing Oracle VM Server (OVS) and Oracle VM Manager (OVM). It then walks through the steps to discover OVS servers, configure storage like NFS, create server pools and repositories, import a template, and clone the template to create a new virtual machine. The document provides information on networking, storage, and troubleshooting Oracle VM.
Oracle RAC and Your Way to the Cloud by Angelo PruscinoMarkus Michalewicz
Angelo Pruscino, SVP Oracle RAC Development, presents the future of Oracle RAC, including some upcoming technologies and their relevance for the (private) database cloud as part of his Keynote during the DOAG 2014 conference.
This document discusses Oracle Real Application Clusters (RAC) and its implementation on Linux. RAC provides scalability, high availability, and increased performance. Key benefits of implementing RAC on Linux include its open source nature, lower costs, and direct technical support from Oracle. The document outlines the hardware, software, and installation steps required to set up Oracle RAC on Linux, including configuring Oracle Cluster File System (OCFS) and Oracle Cluster Management System (OCMS).
Oracle RAC 12c Best Practices with Customer Example (Sanger) as presented during Oracle Open World 2013 (OOW13).
This is part one of the Oracle RAC 12c "reindeer series" used for OOW13 Oracle RAC-related presentations.
Oracle ACFS High Availability NFS Services (HANFS) Part-IAnju Garg
To satisfy increasing demands for data storage from big data and IoT, Oracle DBAs will need to handle massive amounts of normal file system storage. While some organizations have adopted open stack storage, others are evaluating options like NAS, NFS or other file systems. Oracle Database 12c R1 introduces ACFS as a high availability NFS file system (HANFS) that allows files on ACFS clusters to be accessed outside the cluster using highly available NFS exports, providing continuous access even if the exporting node fails.
The document describes managing the Oracle Automatic Storage Management (ASM) instance. It discusses initializing and starting the ASM instance, creating and dropping ASM disk groups, adding and removing disks from disk groups, and retrieving ASM metadata. The key benefits of ASM include eliminating tasks such as file system management and performance tuning of storage.
The biggest headine at the 2009 Oracle OpenWorld was when Larry Ellison announced that Oracle was entering the hardware business with a pre-built database machine, engineered by Oracle. Since then businesses around the world have started to use these engineered systems. This beginner/intermediate-level session will take you through my first 100 days of starting to administer an Exadata machine and all the roadblocks and all the success I had along this new path.
This document provides an overview of implementing Oracle 10g RAC with Automatic Storage Management (ASM) on AIX. It describes ASM, which allows Oracle databases to store data in raw device files that are managed by ASM for striping and mirroring. The document discusses storage and administration considerations for using ASM, tuning parameters, and provides a sample ASM installation process and references.
IOUG Collaborate 18 - ASM Concepts, Architecture and Best PracticesPini Dibask
Pini Dibask presented on Oracle ASM concepts, architecture, and best practices. Some key points:
- ASM is Oracle's recommended storage management solution and provides high performance storage for single-instance and RAC databases.
- ASM uses disk groups and stripes and mirrors data across disks for redundancy and load balancing. It also rebalances data automatically during storage changes.
- Administering ASM involves tasks like starting and stopping the ASM instance, managing disk groups and disks, and monitoring storage usage and I/O balance.
- Best practices for ASM include using separate disk groups for data and recovery files, ensuring consistent disk performance, monitoring I/O balance, and in
Real Application Clusters (RAC) allow an Oracle database to run across multiple interconnected servers that appear as a single database to users. RAC provides high availability, scalability, and manageability. There are two types of RAC configurations: active/passive where one node is active and the other passive, and active/active where instances run concurrently on both servers and clients can access both. Automatic Storage Management (ASM) is an Oracle technology that manages disk storage for Oracle databases.
Updated study material available for 1Z0-027 Exam-Oracle Exadata Database Machine Administration, Software Release visit@ https://www.troytec.com/1Z0-027-exams.html
The document discusses best practices for running Oracle databases on VMware virtual machines. It recommends: 1) carefully sizing workloads based on physical constraints; 2) optimizing ESXi host settings like disabling unnecessary processes, using large memory pages, and matching vCPUs to sessions; 3) optimizing the guest operating system; 4) using dedicated storage like SSDs and aligning datastores; and 5) separating infrastructure and VM network traffic using features like NIC teaming.
This document provides an overview of Oracle database concepts and tools. It describes the core components of an Oracle database including the database, server processes, memory structures, and client/server architecture. It also outlines the tools used to configure an Oracle database such as the Oracle Universal Installer, Database Configuration Assistant, and command line utilities. Automatic Storage Management (ASM) is discussed as the preferred storage management solution.
- ACFS (Oracle Automatic Storage Management Cluster File System) is a file system that extends Oracle ASM functionality to support files outside the database. It can be used to store E-Business Suite application files.
- While not officially certified for E-Business Suite, customers have reported improved performance and availability when using ACFS compared to NFS. Oracle does not prevent its use or deny support for application issues.
- To implement, install an Oracle Grid Infrastructure cluster, create an ACFS file system within an ASM disk group, mount and configure permissions for the E-Business Suite application tier nodes.
Similar to 🔴Oracle ASM Filter Driver & ASMLIB & UDEV🔴.pdf (20)
Recovering a Oracle datafile without backup.pdfAlireza Kamrani
This document describes how to recover an Oracle database file without a backup by:
1. Creating an empty file with the same size as the damaged file using ALTER DATABASE.
2. Performing media recovery on the empty file to apply archived redo logs and restore the data.
3. After recovery, the database can be opened with a resetlogs.
♨️How To Use DataPump (EXPDP) To Export From Physical Standby….pdfAlireza Kamrani
This document provides steps to successfully export data from a physical standby database using Data Pump Export (EXPDP). It explains that EXPDP cannot be run directly on the physical standby due to its read-only status, so a database link must be used to connect from a non-standby database. The physical standby must be opened in read-only mode before exporting. Example commands are given to create a database link, open the physical standby read-only, and run EXPDP with the NETWORK_LINK parameter to export the data. Common errors that can occur without using these steps are also described.
♨️CPU limitation per Oracle database instanceAlireza Kamrani
Cgroups improve database performance by associating a dedicated set of CPUs and memory to a database instance, limiting each instance to only those resources. The setup_processor_group.sh script is used to create cgroups on Linux systems. To bind a database instance to a cgroup, the PROCESSOR_GROUP_NAME parameter must be set to the cgroup name and the instance restarted. Best practices include configuring cgroups out of CPU threads from minimum cores/sockets and creating cgroups with at least 2 CPU cores.
Out-of-Place Oracle Database Patching and Provisioning Golden ImagesAlireza Kamrani
Out-of-place Oracle database patching involves creating a new Oracle Home, applying patches to it, and updating the Oracle Inventory. Golden images can then be created by cloning an existing Oracle Home or Grid Home. Additional Oracle features can be provisioned using the -apply_ru option after applying patches to the golden image. These techniques help minimize downtime and maintain consistency when upgrading Oracle databases.
IO Schedulers (Elevater) concept and its affection on database performanceAlireza Kamrani
I/O schedulers in Linux reorder and group I/O requests to improve throughput while balancing latency. Different schedulers take different approaches, and there is no single best scheduler for all situations. For Oracle databases on Linux, Oracle recommends using the Deadline scheduler for HDD storage to prioritize I/O requests, while the none scheduler may be best for SSD/NVMe storage. When selecting a scheduler, it is important to consider the storage media and I/O characteristics of the workload.
Towards an Analysis-Ready, Cloud-Optimised service for FAIR fusion dataSamuel Jackson
We present our work to improve data accessibility and performance for data-intensive tasks within the fusion research community. Our primary goal is to develop services that facilitate efficient access for data-intensive applications while ensuring compliance with FAIR principles [1], as well as adoption of interoperable tools, methods and standards.
The major outcome of our work is the successful creation and deployment of a data service for the MAST (Mega Ampere Spherical Tokamak) experiment [2], leading to substantial enhancements in data discoverability, accessibility, and overall data retrieval performance, particularly in scenarios involving large-scale data access. Our work follows the principles of Analysis-Ready, Cloud Optimised (ARCO) data [3] by using cloud optimised data formats for fusion data.
Our system consists of a query-able metadata catalogue, complemented with an object storage system for publicly serving data from the MAST experiment. We will show how our solution integrates with the Pandata stack [4] to enable data analysis and processing at scales that would have previously been intractable, paving the way for data-intensive workflows running routinely with minimal pre-processing on the part of the researcher. By using a cloud-optimised file format such as zarr [5] we can enable interactive data analysis and visualisation while avoiding large data transfers. Our solution integrates with common python data analysis libraries for large, complex scientific data such as xarray [6] for complex data structures and dask [7] for parallel computation and lazily working with larger that memory datasets.
The incorporation of these technologies is vital for advancing simulation, design, and enabling emerging technologies like machine learning and foundation models, all of which rely on efficient access to extensive repositories of high-quality data. Relying on the FAIR guiding principles for data stewardship not only enhances data findability, accessibility, and reusability, but also fosters international cooperation on the interoperability of data and tools, driving fusion research into new realms and ensuring its relevance in an era characterised by advanced technologies in data science.
[1] Wilkinson, M., Dumontier, M., Aalbersberg, I. et al. The FAIR Guiding Principles for scientific data management and stewardship. Sci Data 3, 160018 (2016) https://doi.org/10.1038/sdata.2016.18
[2] M Cox, The Mega Amp Spherical Tokamak, Fusion Engineering and Design, Volume 46, Issues 2–4, 1999, Pages 397-404, ISSN 0920-3796, https://doi.org/10.1016/S0920-3796(99)00031-9
[3] Stern, Charles, et al. "Pangeo forge: crowdsourcing analysis-ready, cloud optimized data production." Frontiers in Climate 3 (2022): 782909.
[4] Bednar, James A., and Martin Durant. "The Pandata Scalable Open-Source Analysis Stack." (2023).
[5] Alistair Miles (2024) ‘zarr-developers/zarr-python: v2.17.1’. Zenodo. doi: 10.5281/zenodo.10790679
[6] Hoyer, S. & Hamman, J., (20
Introduction to Data Science
1.1 What is Data Science, importance of data science,
1.2 Big data and data Science, the current Scenario,
1.3 Industry Perspective Types of Data: Structured vs. Unstructured Data,
1.4 Quantitative vs. Categorical Data,
1.5 Big Data vs. Little Data, Data science process
1.6 Role of Data Scientist
Big Data and Analytics Shaping the future of PaymentsRuchiRathor2
The payments industry is experiencing a data-driven revolution powered by big data and analytics.
Here's a glimpse into 5 ways this dynamic duo is transforming how we pay.
In essence, big data and analytics are playing a pivotal role in building a future filled with faster, more secure, and convenient payment methods for everyone.
Data analytics is a powerful tool that can transform business decision-making across industries. Contact District 11 Solutions, which specializes in data analytics, to make informed decisions and achieve your business goals.
Harnessing Wild and Untamed (Publicly Available) Data for the Cost efficient ...weiwchu
We recently discovered that models trained with large-scale speech datasets sourced from the web could achieve superior accuracy and potentially lower cost than traditionally human-labeled or simulated speech datasets. We developed a customizable AI-driven data labeling system. It infers word-level transcriptions with confidence scores, enabling supervised ASR training. It also robustly generates phone-level timestamps even in the presence of transcription or recognition errors, facilitating the training of TTS models. Moreover, It automatically assigns labels such as scenario, accent, language, and topic tags to the data, enabling the selection of task-specific data for training a model tailored to that particular task. We assessed the effectiveness of the datasets by fine-tuning open-source large speech models such as Whisper and SeamlessM4T and analyzing the resulting metrics. In addition to openly-available data, our data handling system can also be tailored to provide reliable labels for proprietary data from certain vertical domains. This customization enables supervised training of domain-specific models without the need for human labelers, eliminating data breach risks and significantly reducing data labeling cost.
Solution Manual for First Course in Abstract Algebra A, 8th Edition by John B...rightmanforbloodline
Solution Manual for First Course in Abstract Algebra A, 8th Edition by John B. Fraleigh, Verified Chapters 1 - 56,.pdf
Solution Manual for First Course in Abstract Algebra A, 8th Edition by John B. Fraleigh, Verified Chapters 1 - 56,.pdf
Annex K RBF's The World Game pdf documentSteven McGee
Signals & Telemetry Annex K for RBF's The World Game / Trade Federations / USPTO 13/573,002 Heart Beacon Cycle Time - Space Time Chain meters, metrics, standards. Adaptive Procedural template framework structured data derived from DoD / NATO's system of systems engineering tech framework
Getting Started with Interactive Brokers API and Python.pdfRiya Sen
In the fast-paced world of finance, automation is key to staying ahead of the curve. Traders and investors are increasingly turning to programming languages like Python to streamline their strategies and enhance their decision-making processes. In this blog post, we will delve into the integration of Python with Interactive Brokers, one of the leading brokerage platforms, and explore how this dynamic duo can revolutionize your trading experience.
Getting Started with Interactive Brokers API and Python.pdf
🔴Oracle ASM Filter Driver & ASMLIB & UDEV🔴.pdf
1. 🔴 Oracle ASM Filter Driver & ASMLIB & UDEV🔴
A complete review, recommendation usage
About Oracle ASM Filter Driver
Oracle ASM Filter Driver (Oracle ASMFD) is a kernel module that resides in the I/O path of the
Oracle ASM disks. Oracle ASM uses the
fi
lter driver to validate write I/O requests to Oracle ASM
disks.
Oracle ASMFD simpli
fi
es the con
fi
guration and management of disk devices by eliminating the
need to rebind disk devices used with Oracle ASM each time the system is restarted.
Oracle ASM Filter Driver rejects any I/O requests that are invalid. This action eliminates accidental
overwrites of Oracle ASM disks that would cause corruption in the disks and
fi
les within the disk
group. For example, the Oracle ASM Filter Driver
fi
lters out all non-Oracle I/Os which could cause
accidental overwrites.
Note : AFD is not compatible with ASMLIB and these packages can't exist together on a OS.
1) Starting with Oracle Grid Infrastructure 12C Release 1 (12.1.0.2), Oracle ASM Filter Driver
(Oracle ASMFD) is installed with an Oracle Grid Infrastructure installation.
2) Oracle Automatic Storage Management Filter Driver (Oracle ASMFD) rejects write I/O requests
that are not issued by Oracle software. This
fi
lter helps to prevent users with administrative
privileges from inadvertently overwriting Oracle ASM disks, thus preventing corruption in Oracle
ASM disks and
fi
les within the disk group. For disk partitions, the area protected is the area on the
disk managed by Oracle ASMFD, assuming the partition table is left untouched by the user.
3) Oracle ASMFD simpli
fi
es the con
fi
guration and management of disk devices by eliminating the
need to rebind disk devices used with Oracle ASM each time the system is restarted.
4) ASMFD is a superset of ASMLIB; therefore it includes base-ASMLIB features (permissions
persistence & sharing open handles).
5) The Oracle ASM
fi
lter driver (ASMFD) is a kernel module that resides in the I/O path of the
2. Oracle ASM disks. Logically, ASMFD provides an interface between Oracle binaries and the
underlying operating environment which includes the storage hardware interfaces. Following are
descriptions of the key capabilities of ASMFD:
• Reject non-Oracle I/Os.
As a manager of Oracle storage, ASM is exposed to the capabilities of the Operating System
(OS) when it comes to dealing with storage devices. In particular, non-Oracle commands have the
ability to overwrite the contents of ASM disks which may lead to unrecoverable data loss. ASMFD
only allows writes using an Oracle-speci
fi
c interface and prevents non-Oracle applications from
writing to ASM disks. This protects ASM from accidental corruption.
• Reduce OS resource usage.
An ASM instance contains numerous processes, or threads on Windows. Without ASMFD, each
process that is I/O capable needs to have its own dedicated open
fi
le descriptor for each disk.
When a database has thousands of processes accessing hundreds of disks, there is an explosion
of
fi
le descriptors leading to considerable OS resource consumption. ASMFD exposes a portal
device that can be used for all I/O on a particular host. The same portal device can be shared by
all the processes associated with multiple database instances. The result is that using ASMFD,
the required number of open
fi
le descriptors is drastically reduced.
• Enable device name persistence.
ASMFD do not require additional con
fi
guration to ensure device name persistence by using udev
rules or third-party storage drivers.
• Faster node recovery.
With the current implementation of Oracle Clusterware, init.d scripts panic the node in situations
when Cluster Synchronization Services (CSS) is not functioning correctly. Using this mechanism,
nodes are fenced to ensure the integrity of the rest of the cluster. While e
ff
ective, this solution is
3. costly because of the time required to reboot the node and restart all the required processes.
ASMFD allows Oracle Clusterware to perform node level fencing without a reboot. So with
ASMFD, it is possible to achieve the same result by restarting the Oracle software stack instead
of rebooting the entire node. This process is just as e
ff
ective, but far quicker.
----------------------
4. ASMLIB:
What is ASMLib?
ASMLib is an optional set of tools and a kernel driver that can be inserted between ASM and the
hardware, as well as an application library used by the Oracle database software to access ASM
disks. It is a support library for the ASM feature of Oracle 10g and higher ,single instance
5. database servers as well as RAC installations. ASM and regular database instances can use
ASMLib as an alternative interface for disk access. ASMLib has three components:
Kernel driver – oracleasm is a Linux kernel driver also known as the Oracle ASMLib kernel driver.
This is an open-source (GPL) kernel driver and is available from Oracle as source and binary
RPMs. Note that although this driver is provided under an open source license, it has not been
accepted into the mainline Linux kernel.
Support tools – oracleasm-support provides the utilities to manage the ASM library driver.
Oracleasm-support is an open-source package (GPL) and is available from Oracle as source and
binary RPMs.
Application library – oracleasmlib package provides the actual ASM library. This is a closed
source, binary-only RPM, available as a free download from Oracle. Oracle introduced ASMLib in
2004 to provide Oracle workloads on Linux with performance and stability comparable to
equivalent workloads on UNIX. ASMLib addressed de
fi
ciencies – including a lack of async and
direct I/O -- that existed in the 2.4 and higher Linux kernel. The Linux community addressed these
de
fi
ciencies in the 2.6 Linux kernel with the addition of udev and device-mapper multipath which
together with LVM provided native multipathing, scalable native volume management, and
persistent device naming. Additionally, the 2.6 Linux kernel added tools for handling large
numbers of disks, especially SAN-attached disks. How is ASMLib delivered? ASMLib is available
as a free download from the Oracle ULN website. Unlike ASM, ASMLib is not included with the
Oracle database product.
ASMLib is available for Linux only; it does not exist for any other platform.
When would I want to use ASM and ASMLib together?
What are the advantages and disadvantages?
Oracle recommends using ASM with ASMLib or AFD together for better manageability and
persistent device naming. Note that Oracle makes no claims that ASM with ASMLib delivers
performance bene
fi
ts over ASM without ASMLib.
Advantages
• Perceived better manageability.
• Well documented and recommended by Oracle.
• Some Oracle DBAs and SysAdmins are trained in how to use ASM with ASMLib and are
comfortable with this environment.
• Optimized for database applications via direct and async I/O provided by the ASMLib kernel
driver.
Note Red Hat Enterprise Linux kernel 2.6.X and higher supports optimized direct and async I/O
for all supported
fi
lesystem EXT3/4, XFS, GFS and NFS.
Disadvantages
• Requires ASMLib kernel driver that is not included in the mainline Linux kernel.
• ASMLib delivers no known performance bene
fi
ts.
• Red Hat Enterprise Linux with ASMLib does not have government security certi
fi
cation.
• ASMLib is not compatible with SELinux.
• ASMLib is not multipath aware and can silently choose to work through a single path, causing
performance and reliability issues.
• Non POSIX system calls for device access lead to issues with trouble-shooting and performance
monitoring.
Can I run an Oracle single instance database with ASM and without ASMLib?
What are the advantages and disadvantages? What are the alternatives?
Yes. It is possible to run an Oracle Single Instance database with ASM and without ASMLib by
specifying udev rules and/or using device mapper multipathing to achieve persistent device
6. naming, both of which are a standard part of Red Hat Enterprise Linux 5 and Red Hat Enterprise
Linux 6 and higher .
ASM can use the following for storage resources:
• Block devices (SATA, SAS, FC, iSCSI, FCoE, regular LUNs and LUNs with thin provisioning) with
udev naming and/or multipathing.
• Raw Devices. • NFS v3 with veri
fi
ed NAS vendors.
Advantages
• Using ASM without ASMLib avoids the overhead resulting from an extra, non-mainline Linux
kernel driver.
• Supported and documented by Oracle.
• Using ASM without ASMLib provides the ability to use operating system's native I/O
multipathing.
• Using POSIX system calls for disk access enables improved performance monitoring and
troubleshooting.
Disadvantages •
Customers may have standardized on Oracle deployments using ASMLib.
Can I use the Oracle single instance database without ASM or ASMLib ? What are my
alternatives? How do I set it up?
Yes. There are two alternatives to using the Oracle single instance database without ASM or
ASMLib:
• Use a local
fi
le system such as ext4.
• Use logical volumes such as provided by lvm2 with dm-multipath or an optional third party
commercial multipathing software. Red Hat will address this con
fi
guration in a forthcoming
reference architecture whitepaper.
Can I use Oracle Real Application Clusters (RAC) with ASM and without ASMLib?
What are my alternatives? How do I set it up?
ASMLib is an optional component of either an Oracle single instance or RAC con
fi
guration. Below
are alternatives to using ASMLib for RAC:
• ASM with LVM: ASM + block devices + udev naming + multipathing.
• Cluster
fi
le systems with cluster volume manager: gfs/clvm (Red Hat Enterprise Linux 5) or
Symantec Cluster File System and Symantec Cluster Server (http://www.symantec.com/business/
storage-foundation-for-oracle-rac).
• NFS v3 with veri
fi
ed NAS vendors.
Red Hat will address this con
fi
guration in a forthcoming reference architecture whitepaper.
Can I use Oracle Real Application Clusters (RAC) without ASM or ASMLib? What are my
alternatives? How do I set it up?
Yes a preferred option is Udev rules.
Although most Oracle RAC installations with SAN-attached storage use ASM, RAC can be
deployed without ASM if database
fi
les are located on an NFS server, certi
fi
ed cluster
fi
le system,
or raw devices. (Note that Oracle discourages the use of raw devices.) Red Hat will address this
con
fi
guration in a forthcoming reference architecture whitepaper.
I already use ASM and ASMLib. How do I migrate from using them to something else?
This is a simple migration.
Perform the following:
1. The DBA stops all database instances using storage through ASM and ASMLib.
2. The system administrator con
fi
gures udev (or multipath) to assign permissions allowing ASM
processes to have read and write access to ASM devices
3. The DBA changes one ASM parameter to point ASM to the assigned devices.
4. The DBA restarts the ASM instance and databases.
7. 5. As with all data-related changes, a backup is highly recommended.
Some theoretical bene
fi
ts of ASMLIB API:
• always uses direct, async i/o
• solves persistent device naming, even if underlying device moves across reboots
• solves
fi
le permissions and ownership
• reduced user mode to kernel mode context switches during I/O, possibly reducing CPU usage
• reduced
fi
le handle usage
• pass metadata such as I/O prioritization to storage device (don’t think this is implemented in the
Linux version)
Note :
using direct i/o and async i/o have dependencies on Oracle parameters Disk_asynch_io =true
and
fi
lesystemio_options=Set All .
----------------------------------
UDEV Rules:
What is Udev?
Udev is the mechanism used to create and name /dev device nodes corresponding to the devices
that are present in the system. Udev uses matching information provided by sysfs with rules
provided by the user to dynamically add the required device nodes.
Udev rules doesn't Linux kernel limitations on upgrade time instead of ASMLIB and AFD
kernel dependencies.
All udev
fi
le should be under /etc/udev/rules.d/
basic format for udev rule is.
key1=”value”, key2=”value”, … keyN=”value”, name=”value”, symlink=”value”
You can
fi
nd the key value by using udevadm command. Lets understand the environment key.
# multipath -ll mpathxy
mpathxy (wwn) dm-6 (vendor)
size=600G features=’1 queue_if_no_path’ hwhandler=’0′ wp=rw
`-+- policy=’service-time 0′ prio=1 status=active
|- 1:0:0:6 sdj 8:1 active ready running
|- 1:0:1:6 sdk 65:2 active ready running
|- 2:0:0:6 sdl 65:14 active ready running
`- 2:0:1:6 sdm 66:24 active ready running
So we have multipath mpathxy and reference device mapper is dm-6.
# udevadm info –query=all –path=/devices/virtual/block/dm-6
Above command will give you list of variables which you can use in udev rules.
You can make the following entry in /etc/udev/rules.d/99-oracle-asmdevices.rules
KERNEL==”dm-*”,ENV{DM_UUID}==”mpath-wwn”,OWNER=”username”,GROUP=”
groupname”,MODE=”0660″
Or you can use following script to create the /etc/udev/rules.d/99-oracle-asmdevices.rules
Generate udev rules for Physical and virtual server
/etc/udev/rules.d/99-oracle-asmdevices.rules
8. KERNEL=="dm-*",ENV{DM_UUID}=="mpath-
wwn",OWNER="oracle",GROUP="oinstall",MODE="0660"
KERNEL=="dm-*",ENV{DM_UUID}=="mpath-
wwn1",OWNER="oracle",GROUP="oinstall",MODE="0660"
# /sbin/udevadm control –reload-rules
# /sbin/udevadm trigger –type=devices –action=change
Now verify the udev rules via
# ls -l /dev/dm*
UDEV Rules Advantages:
• Using ASM without ASMLib avoids the overhead resulting from an extra, non-mainline Linux
kernel driver.
• Supported and documented by Oracle.
• Using ASM without ASMLib provides the ability to use operating system’s native I/O
multipathing.
• Using POSIX system calls for disk access enables improved performance monitoring and
troubleshooting.
. There are no issues linux kernel upgrades on Asmlin & Asm
fi
lter drive.
UDEV Rules Disadvantages:
• Customers may have standardized on Oracle deployments using ASMLib.
-----------------------------------
♨ My experience:
You may
fi
nd i/o tests and some benchmarks on using ASMLIB or ASM Filter Drive that speaks
about performance better as a result .
Normally these i/o testing leads to AFD has better performance instead of ASMLIB. And ASMLIB
usage is better performance instead of UDEV Rules.
Generally, ASM Filter Drive is very dependent on Grid version and not always available to you, but
its features is noticeable and seductive for DBA.
Although isolation levels , security features on AFD is a good feature, But you should consider
that these performance benchmarks is very dependent on hardware and resources, so this not
meaning that using them also is better performance for your environment,
fi
nally with attention to
linux kernel and oracle grid upgrades and issues on AFD and ASMLIB, you can consider to use
only UDEVs + Multipathing on Linux and DBA must consider maintenance cost of there tools with
respect to its features also.
Therefore , on new kernel and Grid versions that support AFD, you can use it and enjoy its
features and when Grid version not supported you can use ASMLIB, but it is possible you force to
change and using Udev rules in the speci
fi
c time in future cause of upgrade your linux or
database.
So dont worry about performance e
ff
ective on using Udev rules instead of ASMLIB or AFD, if realy
there tools give us a performance rate, this feature instead of minimizing maintenance cost on
future is a right and rational decision.
About Migrating to Oracle ASM Filter Driver From ASMLIB
If Oracle ASMLIB was installed, but not used earlier, you must create disk labels to enable
migration of Oracle ASM disk groups to Oracle ASM Filter Driver (Oracle ASMFD) after installing
Oracle Grid Infrastructure 12c Release 1 (12.1.0.2).
Oracle recommends that you temporarily move Oracle Cluster Registry (OCR) and voting
fi
les to
another disk group if one is available, as described in "https://docs.oracle.com/en/database/
oracle/oracle-database/12.2/ostmg/administer-
fi
lter-driver.html#GUID-9C370239-C67D-4813-
BE83-B0528397C02D
9. and migrate the disk group to use Oracle ASMFD. After migrating the disk group to use Oracle
ASMFD, move OCR and voting
fi
les back to the disk group. You can similarly migrate any other
disk groups if they contain OCR or voting
fi
les to ensure online migration of all disk groups to
Oracle ASMFD.
Regarding
Alireza Kamrani.