[linux-lvm] Horrid performance with 2.4.{9,10,12} + LVM + ReiserFS
Werner John
john at oswf.de
Thu Oct 18 09:17:43 UTC 2001
Jens Benecke writes:
> Hello,
Hello,
> this is CC'ed to LVM user list and ReiserFS because I don't know who to
> blame currently. ;)
>
lets, see ...
>
> I have severe performance problems with a 210G ReiserFS volume sitting on a
> LVM (1.0.1rc4) spread over three disks (Maxtor 60, 80, 80GB IDE). The
> system is a Duron 650MHz with via686b chipset and UDMA-100 capable IDE.
> /proc/cpuinfo, /proc/ide/via output see below. The hardware seems
> performant enough to me.
> [...]
>
> ---------------------------------------------------------------------------
> hdparm output for the three disks:
>
> server: /home# hdparm -tT /dev/hd[abcd]
> /dev/hda:
> Timing buffer-cache reads: 128 MB in 0.86 seconds =148.84 MB/sec
> Timing buffered disk reads: 64 MB in 2.12 seconds = 30.19 MB/sec
> /dev/hdc:
> Timing buffer-cache reads: 128 MB in 0.84 seconds =152.38 MB/sec
> Timing buffered disk reads: 64 MB in 2.28 seconds = 28.07 MB/sec
> /dev/hdd:
> Timing buffer-cache reads: 128 MB in 0.86 seconds =148.84 MB/sec
> Timing buffered disk reads: 64 MB in 2.36 seconds = 27.12 MB/sec
Well, you have 1 disk on a single channel (hda) and the other two as master
and slave on *one* channel. That's the bottleneck. If the disks are
accessed individually, you get the full performance (more or less). But if
*both* disks have to respond, performance drops horribly.
Best is to get a third IDE controller.
Yours,
Werner
>
>
> bonnie++ output for the LVM volume: ---------------------------------------
> Version 1.01d ------Sequential Output------ --Sequential Input- --Random-
> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
> server 256M 5596 97 24539 34 6926 7 5194 87 24662 17 115.1 1
> ------Sequential Create------ --------Random Create--------
> -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
> 16 7965 99 +++++ +++ 10546 99 5458 92 +++++ +++ 8214 90
> server,256M,5596,97,24539,34,6926,7,5194,87,24662,17,115.1,1,16,7965,99,+++++,++
> ---------------------------------------------------------------------------
>
>
>
>
> --
> Jens Benecke ········ http://www.hitchhikers.de/ - Europas Mitfahrzentrale
>
> Crypto regulations will only hinder criminals who obey the law.
>
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