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

From: Binley Lim <Binley.Lim_at_xtra.co.nz>
Date: Wed, 19 Apr 2006 14:10:36 +1200
Message-ID: <00ec01c66356$8fde84e0$f74236d2@csnqusvf>


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.

> 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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Received on Tue Apr 18 2006 - 21:10:36 CDT

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