[linux-lvm] LVM and *bad* performance (no striping)

[Andreas Dilger]

Urs writes:
> Sorry, I hadn't time to test your patch earlier.  I wanted to try it
> yesterday but lvm-0.9.1-beta7 with your patch applied doesn't compile.

Sorry, I must have missed some parts of the patch for the user-space
tools.  Even so, I don't think the patch will help.

> I also did some tests with another hard disk drive.  My previous tests
> were with a IBM DCAS-34330W SCSI-U2W.  I now did some tests with a NEC
> DSE2100S SCSI2 drive.  Again, LVM is much slower with the standard
> 512 byte block size:

One other person had a similar problem.  It was because they were
using PIO mode instead of DMA mode on their (IDE) drive.  However,
I see you are using a SCSI disk, so I don't know what to suggest...

What SCSI controller are you using?

> And am I really the only one who sees this?  I would really be
> interested to hear from some more people about performance for their
> LVM.

I have never seen more than a few percent difference between LVM and
non-LVM performance.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert