[linux-lvm] LVM2 seems to chop performance by 33%

[Chris Croswhite]

try bs=64k, even better...

On Thu, 2004-06-10 at 08:05, Stuart Harper wrote:
> While doing backups of my LVM2 drive, I've found that setting the DD block 
> size to 4096 greatly improved my performance. Formerly, DDs on my 240G LVM 
> were taking 23hrs to complete with a block size of 512 or 1024. The same 
> volume now takes less than 2 hours with a block size of 4096. Large numbers 
> did not seem to increase DD speed.
> 
> On Thursday 10 June 2004 10:25 am, David Greaves wrote:
> > 65Mb/s on the raid5 device
> > 44Mb/s on the lv
> >
> > Is this expected?
> >
> > Kernel 2.6.6
> >
> > representative dd's:
> >
> > cu:/huge/editing/tmp# time dd if=/dev/video_vg/video_lv of=/dev/null
> > bs=1024k count=4k
> > David
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