Re: HP LVM and Oracle

In article <3usqip$9rm_at_ixnews4.ix.netcom.com>, bmcdan_at_ix.netcom.com (Brian Mc Daniel) wrote:

> Does anyone know what Oracle's recommendation is on the use of LVM. If
> I extend the filesystem for a database instance which makes it extend
> to another physical drive does this hamper performance on any great
> scale. Are there any experiences out there with admins implementing
> disk mirroring with LVM and noticing increased performance on a read
> intensive app.
>
> Thanks,
> Brian

Brian,
We use the LVM and RAID. We have discover many interesting things. First ORACLE doesnt really have a good handle on platform specific tuning issues. So ORACLE probably wont have any hard facts for you, just some helpful hints. HP on the otherhand maybe able to give you a few more platform insights.

If you think about it, ORACLE has its own algorithm it uses to go to the disks, The LVM has its algorithium, and RAID has its own as well. And it you have all three they are probably competing. So what can you do.

Well one thought process says to make sure you have as many I/O paths to the disk as possible to prevent I/O contention. Another is to stripe drives for performance, another to put real busy tablespaces on their own stripeset etc.

To answer your question, I have not seen any performance degredation when my datafiles span disks via LVM, however I also have some that are stripesets and some that are RAID. I have seen the RAID run a bit slower.

Steve Lemme
DBA/Systems Manager
Motorola

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