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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Cluster File System Versus ASM for RAC Deployment in Production?... Pros & Cons
Sorry--I forgot to also include that I completely agree with Matt's comments about using ASM + a CFS--especially to support a secondary archivelog destination. I sometimes also use a local (non-shared) filesystem for a secondary archivelog destination if a CFS isn't available. Some customers don't like to add the additional "special" software required to support the CFS in an already-complex environment.
Good comments, Matt.
Dan
>> However, OCFS2 has no capability
for growing filesystems, creating situations where using OCFS2 for
datafiles means increasing the number of mounts over time, which gets
messy.
That's incorrect. "tunefs.ocfs2 -S /dev/sde1" will grow the FS to the size of the partition where it resides. Just tested it this week:
[root_at_ch-srlxdb01 ~]#
tunefs.ocfs2 -S /dev/sde1
tunefs.ocfs2 1.2.7
Changing volume size from
1309649 blocks to 1834541 blocks
Proceed (y/N): y
Resized volume
Wrote Superblock
I always recommend using both ASM and a CFS, where appropriate. For example, on Linux systems, where there is a free, Oracle-supported CFS (OCFS2), I recommend making a small OCFS2 filesystem (or two) for storage of OCR and voting files. Then, make the primary datafile/index/log storage on ASM. Optionally, they can then have a large dump or backup filesystem that is OCFS2, or NFS - but I always recommend keeping an archive location outside of ASM, so if the ASM instance won't start up, you can at least get to your archive logs, and presumably you're doing backups or a standby database somewhere.
The reason for using both ASM and CFS on Linux is because dealing with multiple block devices for the various OCR and Voting devices is annoying and complex, and typically you'll end up wasting a lot of disk space (i.e. allocating an 8GB lun for a 100MB ocr device). By using a clustered file system, you can put multiple objects on the one disk, and if necessary, store other things there. However, OCFS2 has no capability for growing filesystems, creating situations where using OCFS2 for datafiles means increasing the number of mounts over time, which gets messy. ASM solves that problem for you by doing very basic striping.
Thanks,
Matt
-- Matthew Zito Chief Scientist GridApp Systems P: 646-452-4090 mzito_at_gridapp.com http://www.gridapp.com -- http://www.freelists.org/webpage/oracle-lReceived on Thu Dec 06 2007 - 08:53:45 CST
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