Jeff Victor wrote:

Brian Kolaci wrote:

Carisdad wrote:


On Fri, Aug 18, 2006 at 08:52:29AM +0200, Robert Milkowski wrote:
Hello Brian,

Wednesday, July 26, 2006, 8:31:06 PM, you wrote:

BK> With the performance boosts included in recent solaris versions I'm BK> told that there's not much of a difference between handing the database
BK> raw devices vs. using a filesystem anymore.

BK> To test this out, my customer would like to try both ufs and vxfs
BK> filesystems in the global zone and lofs mount them to a local zone
BK> and test the database on that lofs mount.

BK> Are there any options that should be supplied for the lofs mount and BK> are there any options for the ufs and/or vxfs mounts that should be BK> employed to assure the performance should be close to raw devices?

1. lofs is probably a bad idea - mount them directly into a zone

lofs is the only supported option for vxfs.

While lofs is the only officially supported option, mounting directly in the zone can be accomplished with a work-around. see:

The customer will only accept officially supported options on this (i.e. lofs). Why exactly would lofs be a bad idea? What is the downside to lofs rather than directly using VxFS? With lofs they get the benefit of the ability to share one filesystem among multiple zones (not at the same mount point in the global zone). But is there anything that would increase/decrease performance by using lofs? Is there a major performance difference to running a database with its storage
on lofs vs. VxFS vs. RAW?

Not an answer, just a clarification: LOFS essentially re-mounts an existing filesystem onto an additional mount-point. When using LOFS, there is always the original fs type to consider. The comparison would then be "a LOFS-mount of a UFS filesystem" vs. "a UFS filesystem" vs. "a raw device." Of course, VxFS can be substituted for UFS.

I guess the direct question would be "a LOFS-mount of a VxFS filesystem with QuickIO enabled". Typically databases want either QuickIO or forcedirectio (on UFS) enabled so that writes aren't buffered. Is that still the case if LOFS is mounted on another filesystem? The DBA's say that writing to a raw device is somewhat equivalent to writing a file on
a filesystem with QuickIO enabled.

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