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From: David Greaves <david@dgreaves.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] LVM2 seems to chop performance by 33%
Date: Thu, 10 Jun 2004 16:34:34 +0100	[thread overview]
Message-ID: <40C87F8A.7080304@dgreaves.com> (raw)
In-Reply-To: <200406101105.47606.StuartHarper@tampabay.rr.com>

Thanks

I'd tried that, but no real change. I started 1t 128k and also tried 
64k, 256k :) (oh, and 1k)

dd if=/dev/video_vg/video_lv of=/dev/null bs=4k count=256k
262144+0 records in
262144+0 records out
1073741824 bytes transferred in 24.130318 seconds (44497624 bytes/sec)

dd if=/dev/md0 of=/dev/null bs=4k count=256k
262144+0 records in
262144+0 records out
1073741824 bytes transferred in 15.404947 seconds (69701105 bytes/sec)

David

PS wait 'til you see what I'm getting through Rieserfs on top of it!
<sigh>
cu:/huge/editing/tmp# time dd if=dummy.deleteme of=/dev/null bs=4k 
count=256k
262144+0 records in
262144+0 records out
1073741824 bytes transferred in 31.627904 seconds (33949193 bytes/sec)
so throughput down by a factor of 2...
but 1 step at a time....

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
>>    
>>
>_______________________________________________
>linux-lvm mailing list
>linux-lvm@redhat.com
>https://www.redhat.com/mailman/listinfo/linux-lvm
>read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>  
>

  parent reply	other threads:[~2004-06-10 15:34 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-06-10 14:25 [linux-lvm] LVM2 seems to chop performance by 33% David Greaves
2004-06-10 15:05 ` Stuart Harper
2004-06-10 15:31   ` Chris Croswhite
2004-06-10 15:34   ` David Greaves [this message]
2004-06-10 16:30     ` Clint Byrum
2004-06-20 18:17       ` David Greaves
2004-06-20 19:53         ` Alasdair G Kergon
2004-06-21  9:55           ` David Greaves
2004-06-14 11:50 ` Miguel Cabeça
2004-06-14 13:24   ` David Greaves

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