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May 23, 2005

Update: RedHat 4.0 includes NFS v4

An update for me anyway, didn't realise this but its there. So, excellent news for linux WebSphere 6.0 customers looking for easy high availability.

http://www.redhat.com/software/rhel/features/

May 23, 2005 in High Availability | Permalink

Comments

Billy

Can you please highlight if there are any significant implications of putting transaction logs on an NFS mounts? In particular,

1) I thought that NFS did not guaranteed that a write would be forced to disk immediately - and hence product vendors would not support their transaction logs being stored on NFS mounts (eg, Oracle)

2) What sort of disk write latency can you expect? Obviously this depends on the underlying disk array, but what additional performance issues does NFS introduce? (Because of point 1 I had never considered putting a tranlog on NFS before)

Cheers
Andrew

Posted by: Andrew Ward | May 25, 2005 7:27:40 AM

1) They can. Both DB2 and Oracle are fully supported on NFS file systems when the NFS mounts and servers are configured properly. Databases. Here are some links illustrating the point:
Oracle on NFS
http://www.netapp.com/tech_library/3189.html
Note the NFS mount settings on the client

DB2 on NFS
http://www.netapp.com/tech_library/3272.html
Note the NFS mount settings on the client

Here Redhat indicates how to make their NFS server guarantee writes are forced before replying
http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/custom-guide/s1-nfs-export.html

2) Depends on the hardware. If you are using a blade then typically its faster over NFS purely because the disk in a blade is usually a laptop drive and isn't particularly fast. Our own tests also indicate that the TM is rarely a performance bottleneck in benchmarks. My own tests using a NetApp f940 as my filer indicates it's actually faster using a NFS filesystem. If you put the NFS server on your database box, it's hard to see the local disks beating it if you use the database disk subsystem for the NFS volume.

Hope this helps.

Posted by: Billy Newport | May 25, 2005 8:51:01 AM

Also see this redbook showing how to put DB2 on NFS servers in a fully supported way.

http://www.redbooks.ibm.com/abstracts/sg246538.html?Open

Posted by: Billy Newport | May 25, 2005 8:57:33 AM

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