I took hdg offline and ran tests on it separately with bonnie and it seems
OK. The array rebuild is really slow - max 15000kB/s and the load average is
over 2. The strange thing is that kswapd is actively running whenever I
perform IO on the array (and my swap file is not used at all). I haven't
noticed this before - I suspect its related to this issue. Any ideas? Enable
himem? (I only have 512MB RAM).
-----------
cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid5]
read_ahead 1024 sectors
md0 : active raid5 hdg1[1] hdk1[3] hdi1[2] hde1[0]
234444288 blocks level 5, 128k chunk, algorithm 2 [4/4] [UUUU]
unused devices: <none>
---------------
mdadm -D /dev/md0 (I got the Debian testing version v.1.7.0 - it doesnt
show 'no-errors' now but maybe its because I've just rebuild the array by
removing hdg and then re-adding it).
/dev/md0:
Version : 00.90.00
Creation Time : Sat Apr 17 12:19:25 2004
Raid Level : raid5
Array Size : 234444288 (223.58 GiB 240.07 GB)
Device Size : 78148096 (74.53 GiB 80.02 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Mon Oct 18 15:10:52 2004
State : dirty
Active Devices : 4
Working Devices : 4
Failed Devices : 1
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 128K
UUID : 775f1dcf:7cbc17ab:86e1e792:669b732f
Events : 0.86
Number Major Minor RaidDevice State
0 33 1 0 active sync /dev/hde1
1 34 1 1 active sync /dev/hdg1
2 56 1 2 active sync /dev/hdi1
3 57 1 3 active sync /dev/hdk1
--
---------- Original Message -----------
From: "Guy" <bugzilla@xxxxxxxxxxxxxxxx>
To: "'Gerd Knops'" <gerti@xxxxxxxxxx>, "'Marc'" <linux-raid@xxxxxxxxxxxxxxxx>
Cc: <linux-raid@xxxxxxxxxxxxxxx>
Sent: Mon, 18 Oct 2004 02:12:30 -0400
Subject: RE: Poor RAID5 performance on new SMP system
> You missed something!
> "State : dirty, no-errors"
>
> Mark,
> If you want, send the output of these 2 commands:
> cat /proc/mdstat
> mdadm -D /dev/md?
>
> Don't forget, with versions of md (or mdadm) older than about 6
> months, the counts get really off! My 14 disk array is fine.....
> Note the: "no-errors"! But: /dev/md2: Version : 00.90.00
> Creation Time : Fri Dec 12 17:29:50 2003 Raid Level : raid5
> Array Size : 230980672 (220.28 GiB 236.57 GB) Device Size :
> 17767744 (16.94 GiB 18.24 GB) Raid Devices : 14 <<LOOK HERE>>
> Total Devices : 12 <<LOOK HERE>> Preferred Minor : 2
> Persistence : Superblock is persistent
>
> Update Time : Wed Oct 13 01:55:40 2004
> State : dirty, no-errors <<LOOK HERE>>
> Active Devices : 14 <<LOOK HERE>>
> Working Devices : 11 <<LOOK HERE>>
> Failed Devices : 1 <<LOOK HERE>>
> Spare Devices : 0 <<LOOK HERE>>
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Number Major Minor RaidDevice State
> 0 8 49 0 active sync /dev/sdd1
> 1 8 145 1 active sync /dev/sdj1
> 2 8 65 2 active sync /dev/sde1
> 3 8 161 3 active sync /dev/sdk1
> 4 8 81 4 active sync /dev/sdf1
> 5 8 177 5 active sync /dev/sdl1
> 6 8 97 6 active sync /dev/sdg1
> 7 8 193 7 active sync /dev/sdm1
> 8 8 241 8 active sync /dev/sdp1
> 9 8 209 9 active sync /dev/sdn1
> 10 8 113 10 active sync /dev/sdh1
> 11 8 225 11 active sync /dev/sdo1
> 12 8 129 12 active sync /dev/sdi1
> 13 8 33 13 active sync /dev/sdc1
> UUID : 8357a389:8853c2d1:f160d155:6b4e1b99
>
> #cat /proc/mdstat
> Personalities : [raid1] [raid5]
> read_ahead 1024 sectors
> md2 : active raid5 sdc1[13] sdi1[12] sdo1[11] sdh1[10] sdn1[9]
> sdp1[8] sdm1[7] sdg1[6] sdl1[5] sdf1[4] sdk1[3] sde1[2] sdj1[1] sdd1[0]
> 230980672 blocks level 5, 64k chunk, algorithm 2 [14/14]
> [UUUUUUUUUUUUUU]
>
> Guy
>
> -----Original Message-----
> From: linux-raid-owner@xxxxxxxxxxxxxxx
> [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Gerd Knops
> Sent: Monday, October 18, 2004 1:37 AM
> To: Marc
> Cc: linux-raid@xxxxxxxxxxxxxxx
> Subject: Re: Poor RAID5 performance on new SMP system
>
> On Oct 17, 2004, at 21:11, Marc wrote:
>
> > Hi,
> > I recently upgraded my file server to a dual AMD 2800+ on a Tyan Tiger
> > MPX
> > motherboard. The previous server was using a PIII 700 on an Intel 440BX
> > motherboard. I basically just took the IDE drives and their controllers
> > across to the new machine. The strange thing is that the RAID-5
> > performance
> > is worse than before! Have a look at the stats below:
> >
>
> [..]
>
> > State : dirty, no-errors
> > Active Devices : 4
> > Working Devices : 4
> > Failed Devices : 1
> > Spare Devices : 0
> >
>
> Unless I am missing something, a disk is missing and the RAID runs
> in degraded (=slower) mode.
>
> Gerd
>
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