[linux-lvm] performance writing to an lv with no file system

Howard Clifford howardclifford at cablespeed.com
Mon Jun 30 21:22:01 UTC 2003


Thank you for the response.

My logical volume is striped - 7 ways.

I am writing to the lv with a simple c program I wrote.

Each write is 7*stripesize, which in this case is 28 blocks.

Any thoughts on how I can get top speeds without mounting and unmounting 
  the volume?


 > Howard,

 > what's the LV layout (linear/striped ?).
 > How do you write to the LV (dd or soemthing).
 > What's the write pattern (sequential ? block size ?)

 > 80MB/sec raw sounds like you use a striped LV.

On Sun, Jun 29, 2003 at 12:08:34PM -0400, Howard Clifford wrote:
 > I built a 7 disk vg and put 1 lv on it.  I do not want to mount a file
 > system.
 > I just want to write directly to the disk device, /dev/vg1/vol1.
 > My write performance has an odd behavior.
 > If after booting I write to the volume I get roughly 175MB/sec.
 > If after booting I do a mke2fs on the volume, mount it, umount it, then
 > write to the volume I get roughly 230 MB/sec.
 > Any ideas?  How can I get top speed without first mounting then
 > umounting the volume?
 > By the way, I tried binding a raw device to the lv and got very bad
 > performance; around 80 MB/sec.  Would that be expected?
 > (I'm using redhat 9.0 -> lvm-1.0.3-12)
 > Thanks...
 > _______________________________________________
 > linux-lvm mailing list
 > linux-lvm at sistina.com
 > http://lists.sistina.com/mailman/listinfo/linux-lvm
 > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/


Heinz    -- The LVM Guy --

*** Software bugs are stupid.
     Nevertheless it needs not so stupid people to solve them ***


Heinz Mauelshagen                                 Sistina Software Inc.
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