RE: Recovery with logs, then incremental, then more logs?

Binley, I don't believe we are using any of the snapshot features, but I could be mistaken. I'll check with the Unix admins. Yes, redo logs are on the same filesystem as archive, along with all datafiles as well - this was done prior to my involvement and apparently they liked the S.A.M.E method a lot. I also like to keep redo and archived logs separate, as I am doing on the new 10g environment I'm implementing right now.

I know the NFS r/wsizes were originally 32K by default, and I suggested that we might want to investigate whether or not they should be reduced to 8k in order to be aligned with the db_block_size since about 95+% of our I/O is single-block reads, but I did not have time to investigate whether or not this would be a wise change and later found that they implemented it anyway w/o ever engaging me further. Have you experienced better performance with larger rsize/wsize?

Thanks!
Brandon

-----Original Message-----
From: Binley Lim [mailto:Binley.Lim_at_xtra.co.nz] Sent: Tuesday, April 18, 2006 7:11 PM
To: Allen, Brandon; Riyaj Shamsudeen
Cc: oracle-l_at_freelists.org
Subject: Re: Recovery with logs, then incremental, then more logs?

Don't know about EMC specifics, but Netapp has a snapshot feature where you are using up additional disk-space each time you do a DML. The original block is "frozen" (contains the snapshot point-in-time), and the copy of the block with the modified data is written out. So now you have 2 blocks instead of one. As you make more changes, you will take up more space.

Fact that you got the no-space-left error when writing to the online redo log sounds suspiciously like the same sort of problem, ie a redo write is actually requiring more space. If this is a snapshot issue, keeping to 10% free will of course avoid this problem. Better still, switch off snapshotting.

Also it appears you have put the redologs on the same volume as the archivelogs. I would prefer to keep them separate, like internal/DAS disks, for these and other reasons vendors don't tell you about. And for performance reasons, also look at increasing rsize/wsize - and EMC should have recommendations on that.

• Original Message ----- From: "Allen, Brandon" <Brandon.Allen_at_OneNeck.com> To: "Riyaj Shamsudeen" <rshamsud_at_jcpenney.com> Cc: <oracle-l_at_freelists.org> Sent: Wednesday, April 19, 2006 10:25 AM Subject: RE: Recovery with logs, then incremental, then more logs?

> Yep, it's an EMC. My Unix admin just told me earlier today that EMC told
him that they recommend keeping the filesystems below 90% full to avoid any problems. I had never heard anything like that before - anyone else? This is a 500GB filesystem, so to keep it below 90% we're talking about wasting 50GB. Not the end of the world, I know, but certainly not ideal and I can't believe that this would actually be a requirement for stability.
>
>
> -----Original Message-----
> From: Riyaj Shamsudeen [mailto:rshamsud_at_jcpenney.com]
>
>
> I don't know much about NFS3 protocol, but is your vendor / file system
> in this list ?
>
>

http://www.oracle.com/technology/deploy/availability/htdocs/vendors_nfs.html

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