When one of my clients is working on a new RAC configuration, I’m guaranteed to receive tons of questions. One of the most common is: what is the best storage option for RAC?
Despite the plethora of articles and information regarding storage options, most companies end up going with the advice of their storage vendor.
Some of these options include:
* Raw storage, which is often demanded yet rarely used. Popular misconceptions and difficult management make this a fading technology.
* ASM, the new standard for RAC storage. As a one-time skeptic of this technology, I have found myself consistently pleased with it.
* Direct NFS, 11g’s new networked storage product sure to excite users of NAS filers.
* OCFS2, a cluster file system developed for Oracle RAC environments.
To read more on these options as well as a discussion on udev rules, a device management solution which replaces traditional methods in RHEL5 see here:
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Popular RAC Storage Options in 11g
Important ASM changes in 11g Release 2
There are some super-important changes to storage management in Oracle 11g Release 2, Oracle ACE Lutz Hartmann has offered the following items that delve into these important new enhancements in 11gR2.
ASM Cluster Filesystem (ACFS) - This new feature allows is also named "Unified Storage Management" (UFS) and allows for storing Application File Data , the Oracle Cluster Registry (OCR), the Cluster Voting Disk, and the Oracle Binaries, all within ASM
Cluster Voting Disk and Cluster Registry in ASM - This is an important RAC enhancement where it is now possible to create Quorum Disk Groups and Quorum Disk FailGroups which cannot hold any other data than OCR or Voting Disk data.
ASM Dynamic Volume Manager (ADVM) - ADVM is a new device driver which is integrated into the Oracle Kernel and functions as a standard I/O interface for normal file systems to utilize ASM functionalities. This driver communicates with the ASM instance about ASM extent maps, rebalancing operations and I/O failure issues.
ASM FS Snapshots in 11gR2 - It is now possible to create up to 63 image copies of file systems as a point in time capture. These snapshots a read only and can be used to view a file system as of the point in time in the past when they were created.
ASM Optimal Disk Placement in 11gR2 - It is now possible to specify on which disk regions the ASM Disks will be placed. This enables us to make use of faster disk zones on the outer regions of disks for better I/O performance.
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