Re: Physical I/O on a SAN or NAS

On 2003-12-05, Ryan Gaffuri <rgaffuri_at_cox.net> wrote:
> We are using an NAS. Are there any conventions to handling Physical
> I/O distribution on NAS or SANs? They are relatively new. Since we
> dont control which disk or mount point datafiles go on, we really
> can't spread out the I/O. Does it matter if we put tables in different

I would expect that there is still some mechanism to divy up logical drives among physical drives. You probably want to isolate sequential access files from random access ones.

IOW, isolate your online redo logs from your tablespace files.

High latency on redo log writes can really clobber performance.

If you dig around the Hitachi website you should be able to find a whitepaper that admits that their storage hardware (probably more efficient than any NAS) is remarkably less efficient while doing random IO activity vs sequential IO activity.

> datafiles then?
>
> any conventions or articles would be helpful.

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