[dm-devel] Problem using dm-multipath on first of 2 LUNs on system

LittleJ at AE.com LittleJ at AE.com
Tue Jan 29 21:40:54 UTC 2008


When I execute `multipath -v3` the following appears in
/var/log/messages:

Jan 29 16:32:50 svwdcvispay01 kernel: device-mapper: dm-multipath: error
getting device
Jan 29 16:32:50 svwdcvispay01 kernel: device-mapper: error adding target
to table
Jan 29 16:32:52 svwdcvispay01 hald[3620]: Timed out waiting for hotplug
event 361. Rebasing to 362
Jan 29 16:33:06 svwdcvispay01 hal.hotplug[22665]: timout(10000 ms)
waiting for /block/dm-5

I am able to perform I/O to both /dev/sda and /dev/sdc:

[root at svwdcvispay01 ~]# dd if=/dev/sda of=/dev/null count=10
10+0 records in
10+0 records out
[root at svwdcvispay01 ~]# dd if=/dev/sdc of=/dev/null count=10
10+0 records in
10+0 records out
[root at svwdcvispay01 ~]#

Joe Little
littlej at ae.com




-----Original Message-----
From: dm-devel-bounces at redhat.com [mailto:dm-devel-bounces at redhat.com]
On Behalf Of malahal at us.ibm.com
Sent: Tuesday, January 29, 2008 2:58 PM
To: dm-devel at redhat.com
Subject: Re: [dm-devel] Problem using dm-multipath on first of 2 LUNs on
system

LittleJ at AE.com [LittleJ at AE.com] wrote:
>    I am attempting to implement dm-multipath on a RHEL4U6 server and I
have
>    been successful in enabling it on the second of 2 LUNs on the
server but
>    for whatever reason it will not create the device special files in
>    /dev/mapper for the fist LUN.  `multipath -d` shows that it
identifies the
>    first LUN and wants to create the mpath0 files:
> 
> 
> 
>    [root at svwdcvispay01 etc]# multipath -d
> 
>    create: mpath0 (36005076801810085c800000000000194)
> 
>    [size=12 GB][features="1 queue_if_no_path"][hwhandler="0"]
> 
>    \_ round-robin 0 [prio=50]
> 
>     \_ 1:0:0:0 sda 8:0  [ready]
> 
>    \_ round-robin 0 [prio=10]
> 
>     \_ 1:0:1:0 sdc 8:32 [ready]

One of the fields (DM path state) is missing from the above output.
Looks like it failed to create mpath0 properly. Make sure you enable
'syslog' and send out the syslog out when you run "multipath -v3" 

Also, can you do read/write I/O to sda and sdc devices? Try reading
data from both of those devices using dd or something similar. The
following should do:

dd if=/dev/sda of=/dev/null count=10
dd if=/dev/sdc of=/dev/null count=10

Thanks, Malahal.

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