Reasons to Use ASM on NFS

Posted in: Technical Track

My tweet from a few days ago: “Personally I don’t see the point building ASM on (d)NFS. ASM suppose to exclude unnecessary layers. In NAS case it adds an additional layer.”

Since then, Oracle people in my Social Media environment have helped me find several legitimate reasons to run ASM on NAS. Thank you folks very much. Now I am sharing our common thoughts with the rest of the community.

Oracle Support

The very first question you will ask is: Does Oracle support putting ASM disks (devices) on NAS?
And the answer is : YES it (surprisingly) does.
Check this out:
Oracle® Database Installation Guide 11g Release 2 (11.2) for Linux Part Number E24321-07
Creating Files on a NAS Device for Use with Oracle Automatic Storage Management.
From that point, the question is not “can we?”. The question is “why?”

Reasons for using ASM on NFS

The following is what we have noted as of now:

  • The license restrictions for Standard Edition. You can use RAC for Free if you follow license restrictions. One of them is to use ASM. If you would like to use NAS as a storage at the same time, you have no other choice but to use ASM on NFS.
  • ASM striping between filers. As simple as it gets. You can use ASM to mirror your data across different storage units. I know, I know. You can do it using NAS vendors’ features. But who knows, maybe someone can’t because of licences or other implications. BTW: This option is valid for any Storage (e.g. SAN).
  • “0” downtime migration from one storage to another. If you use ASM as opposite to datafiles located directly on NFS, you could use ASM rebalancing across ASM disks located on different storage units to migrate your database with zero downtime. You will need ~5 minutes downtime in the case of files located directly on NFS.
  • RAC on NAS. We need at least one ASM disk group to be created for OCR and voting disks.
    • Correction (thanks to Leighton L. Nelson): If you want to run RAC on NAS you can use either ASM or kNFS.
    • Ref: Overview of Oracle Clusterware and Oracle RAC Storage Options from Oracle® Grid Infrastructure Installation Guide 11g Release 2 (11.2) for Linux Part Number E22489-08

Please feel free to comment, especially if you know other reasons for creating ASM on NFS or see any mistake in my blog post.

Yury

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About the Author

Yury is a nice person who enjoys meeting and working with people on challenging projects in the Oracle space. He started to work as an Oracle DBA 14 years ago (1997). For the past 10 years (since 2001) his main area of expertise is Oracle e-Business Suite. Yury is an OCP 7,8,9,10g and OCM 9i,10g. He is a frequent presenter at Oracle related conferences such as Hotsos, UKOUG and AUOUG. Yury is a socially active person. Apart from Social Media (Twitter, Bloging, Facebook) he is the primary organizer of Sydney Oracle Meetup group (250 people). So if you happen to be in Sydney (Australia) drop Yury a message and stop by at one of his Meetups.

2 Comments. Leave new

Long time ago – when 11.1 was bleeding edge – I wanted to try Extended RAC with ASM mirroring redundancy between 2 NFS mountpoints (+ using DNFS) for strictly learning purposes … but I’ve ended up with iSCSI ;)

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Are there performance penalties running Oracle ASM on NFS? | The Pythian Blog
November 6, 2012 8:38 pm

[…] You may ask “Why anyone would consider placing ASM files on NFS and if it is possible at all?” It appears that there are legitimate reasons for doing that and Oracle supports it. You could find additional information under the following blog post Reasons for using ASM on NFS. […]

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