From: "Jaime Peñalba" <jpenalba@corenetworks.es>
To: linux-raid@vger.kernel.org
Cc: neilb@cse.unsw.edu.au
Subject: Re: Multipath problems with 2.6.8.1
Date: Thu, 09 Sep 2004 20:25:17 +0200 [thread overview]
Message-ID: <4140A00D.5030406@corenetworks.es> (raw)
In-Reply-To: <200409091559.i89FxF332735@watkins-home.com>
Im using multipath for failover, not for round robin (rr over multipath
isnt supported with the latest stable kernel), also i was wondering
about how this should be configured before sending a mail to the list,
so i tested both ways (as "2 raid disks" and as "raid disk with spare
disk"), the good way is using a spare disk, or i think so. On raidtools2
there is an example for multipath and they use a spare disk, and it has
sense, because it should act as a spare disk like on a raid 1/5, it uses
the raid disk path, and if it fails, it uses the spare disk path.
Anyway here is the output doing it as 2 raid disks
1) create md
apache2:~# mdadm --create /dev/md0 --force --level multipath
--raid-devices 2 /dev/sdb1 /dev/sdd1
mdadm: array /dev/md0 started.
apache2:~# cat /proc/mdstat
Personalities : [multipath]
md0 : active multipath sdd1[1] sdb1[0]
10485632 blocks [2/2] [UU]
unused devices: <none>
---------
The output from dmesg
md: bind<sdb1>
md: bind<sdd1>
multipath: array md0 active with 2 out of 2 IO paths
And it should be something like this (configured with spare)
md: bind<sdb1>
md: bind<sdd1>
multipath: array md0 active with 1 out of 1 IO paths
MULTIPATH conf printout:
--- wd:1 rd:1
disk0, o:1, dev:sdb1
MULTIPATH conf printout:
--- wd:1 rd:1
disk0, o:1, dev:sdb1
2) stop md
apache2:~# mdadm -S /dev/md0
3) start md again
apache2:~# mdadm --assemble /dev/md0 /dev/sdb1 /dev/sdd
mdadm: failed to add /dev/sdb1 to /dev/md0: Device or resource busy
mdadm: /dev/md0 has been started with 2 drives and -1 spares.
apache2:~# cat /proc/mdstat
Personalities : [multipath]
md0 : active multipath sdd1[0]
10485632 blocks [1/1] [U]
unused devices: <none>
-------------------------------
Superblocks info
apache2:~# mdadm -E /dev/sdb1
/dev/sdb1:
Magic : a92b4efc
Version : 00.90.00
UUID : 57d730b7:49b3d124:b5d30806:127c5bc3
Creation Time : Thu Sep 9 19:49:10 2004
Raid Level : multipath
Device Size : 10485632 (10.00 GiB 10.74 GB)
Raid Devices : 2
Total Devices : 1
Preferred Minor : 0
Update Time : Thu Sep 9 20:16:37 2004
State : dirty
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Checksum : 9626eafd - correct
Events : 0.45
Number Major Minor RaidDevice State
this 0 8 49 0 active sync /dev/sdd1
0 0 8 49 0 active sync /dev/sdd1
1 1 0 0 1 faulty removed
-----------------------
apache2:~# mdadm -E /dev/sdd1
/dev/sdd1:
Magic : a92b4efc
Version : 00.90.00
UUID : 57d730b7:49b3d124:b5d30806:127c5bc3
Creation Time : Thu Sep 9 19:49:10 2004
Raid Level : multipath
Device Size : 10485632 (10.00 GiB 10.74 GB)
Raid Devices : 2
Total Devices : 1
Preferred Minor : 0
Update Time : Thu Sep 9 20:16:37 2004
State : dirty
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Checksum : 9626eafd - correct
Events : 0.45
Number Major Minor RaidDevice State
this 0 8 49 0 active sync /dev/sdd1
0 0 8 49 0 active sync /dev/sdd1
1 1 0 0 1 faulty removed
As you can see both paths points to the same disk, because sdb1 has the
sdd1 superblock, that is the last superblock wroten.
Jaime.
Guy wrote:
>Somehow you confused it! And me.
>
>You used multipath and spare, but only listed 2 devices.
>I don't think a multipath array can have a spare disk.
>
>Are you sure the 2 paths point to the same disk?
>
>I have never user multipath, so I am just guessing.
>
>If you have no data you need to save yet, try this:
>mdadm --create /dev/md0 --force --level multipath /dev/sdb1 /dev/sdd1
>or
>mdadm --create /dev/md0 --force --level multipath --raid-devices=2 /dev/sdb1
>/dev/sdd1
>
>Guy
>
>-----Original Message-----
>From: linux-raid-owner@vger.kernel.org
>[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Jaime Peñalba
>Sent: Thursday, September 09, 2004 11:33 AM
>To: linux-raid@vger.kernel.org
>Cc: neilb@cse.unsw.edu.au
>Subject: Multipath problems with 2.6.8.1
>
>Hi,
>
>Im having some troubles with multipath on a 2.6.8.1 linux kernel.
>
>Im using 2 QLogic 2344 connected to the SAN, i think that my problem is
>related to superblocks, because when i create a new multipath device, it
>writes the superblock for both disks and really is the same disk trought
>two paths. I have else tried to disable persistent superblock, but mdadm
>doesnt support multipath with the build mode.
>
>Im doing it like this
>
>1) Start the md
>apache1:~/soft/mdadm-1.7.0# mdadm --create /dev/md0 --force --level
>multipath --raid-devices=1 /dev/sdb1 --spare-devices=1 /dev/sdd1
>mdadm: array /dev/md0 started.
>
>apache1:~/soft/mdadm-1.7.0# cat /proc/mdstat
>Personalities : [multipath]
>md0 : active multipath sdd1[1] sdb1[0]
> 4882304 blocks [1/1] [U]
>
>unused devices: <none>
>
>This is ok and runs fine, But superblock is only at /dev/sdd1, so no
>remount would be possible, or i think so...
>
>apache1:~/soft/mdadm-1.7.0# mdadm -E /dev/sdb1
>mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc, got
>00000000)
>
>apache1:~/soft/mdadm-1.7.0# mdadm -E /dev/sdd1
>/dev/sdd1:
> Magic : a92b4efc
> Version : 00.90.00
> UUID : af3395fd:fac2b820:2ca7083c:612864e0
> Creation Time : Thu Sep 9 17:20:43 2004
> Raid Level : multipath
> Device Size : 4882304 (4.66 GiB 5.00 GB)
> Raid Devices : 1
> Total Devices : 2
>Preferred Minor : 0
>
> Update Time : Thu Sep 9 17:20:43 2004
> State : dirty
> Active Devices : 1
>Working Devices : 2
> Failed Devices : 0
> Spare Devices : 1
> Checksum : 63bc7489 - correct
> Events : 0.36
>
>
> Number Major Minor RaidDevice State
>this 1 8 49 1 spare /dev/sdd1
> 0 0 8 17 0 active sync /dev/sdb1
> 1 1 8 49 1 spare /dev/sdd1
>
>
>
>2) Stop the md
>apache1:~/soft/mdadm-1.7.0# mdadm -S /dev/md0
>
>
>3) Start the md again
>apache1:~/soft/mdadm-1.7.0# mdadm --assemble /dev/md0
>--uuid=af3395fd:fac2b820:2ca7083c:612864e0 /dev/sdb1 /dev/sdd1
>mdadm: no RAID superblock on /dev/sdb1
>mdadm: /dev/sdb1 has wrong uuid.
>mdadm: /dev/md0 has been started with 1 drive.
>
>
>apache1:~/soft/mdadm-1.7.0# cat /proc/mdstat
>Personalities : [multipath]
>md0 : active multipath sdd1[0]
> 4882304 blocks [1/1] [U]
>
>unused devices: <none>
>
>Now things arent working very well....
>
>apache1:~/soft/mdadm-1.7.0# mdadm --detail /dev/md0
>/dev/md0:
> Version : 00.90.01
> Creation Time : Thu Sep 9 17:20:43 2004
> Raid Level : multipath
> Array Size : 4882304 (4.66 GiB 5.00 GB)
> Raid Devices : 1
> Total Devices : 1
>Preferred Minor : 0
> Persistence : Superblock is persistent
>
> Update Time : Thu Sep 9 17:26:21 2004
> State : clean
> Active Devices : 1
>Working Devices : 1
> Failed Devices : 0
> Spare Devices : 0
>
>
> Number Major Minor RaidDevice State
> 0 8 49 0 active sync /dev/sdd1
> UUID : af3395fd:fac2b820:2ca7083c:612864e0
> Events : 0.37
>
>
>I would appreciate very much any help with this.
>
>Thanks,
>Jaime.
>
>
>
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next prev parent reply other threads:[~2004-09-09 18:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <S265098AbUIIOeH/20040909143407Z+1912@vger.kernel.org>
2004-09-09 15:32 ` Multipath problems with 2.6.8.1 Jaime Peñalba
2004-09-09 15:59 ` Guy
2004-09-09 18:25 ` Jaime Peñalba [this message]
2004-09-09 16:05 ` Jaime Peñalba
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