[linux-lvm] Mirror fail/recover test SOLVED

jose nuno neto jose.neto at liber4e.com
Tue Mar 2 10:31:03 UTC 2010


Hi
Much thanks for your insights, you're right
multipath was keep the I/O on queue and lvm didn't fail the mirror

I had to create a device section on multipath.conf so that the features=0
would be on used by multipath
Best Regards
Jose

> jose nuno neto [jose.neto at liber4e.com] wrote:
>> Much thanks for your interest
>> im putting more info below
>>
>> > jose nuno neto [jose.neto at liber4e.com] wrote:
>> >> Hi
>> >>
>> >> I'm trying to test the failure of a SAN Mirrored Lv, and the recover
>> and
>> >> check for data lost.
>> >>
>> >> Im runing RedHat 5.4
>> >> 2.6.18-164.2.1.el5
>> >> lvm2-2.02.46-8.el5_4.1
>>
>> multipath -l -v2 | grep -A 7 3600a0b800048f9b200000c2b4b5980b7
>> mpath12 (3600a0b800048f9b200000c2b4b5980b7) dm-8 SUN,CSM200_R
>> [size=52G][features=1 queue_if_no_path][hwhandler=1 rdac][rw]
>> \_ round-robin 0 [prio=0][enabled]
>>  \_ 7:0:1:1  sdo  8:224  [active][undef]
>>  \_ 9:0:1:1  sdq  65:0   [active][undef]
>> \_ round-robin 0 [prio=0][enabled]
>>  \_ 7:0:0:1  sdd  8:48   [active][undef]
>>  \_ 9:0:0:1  sdf  8:80   [active][undef]
>>
>> Before UnPluging
>> dmsetup status mpath12
>> 0 109051904 multipath 2 0 0 0 2 1 E 0 2 0 8:224 A 0 65:0 A 0 E 0 2 0
>> 8:48
>> A 0 8:80 A 0
>>
>> echo offline > /sys/block/sdd/device/state
>> echo offline > /sys/block/sdo/device/state
>> echo offline > /sys/block/sdq/device/state
>> echo offline > /sys/block/sdf/device/state
>>
>> dmsetup status mpath12
>> 0 109051904 multipath 2 0 0 0 2 1 E 0 2 0 8:224 F 1 65:0 F 1 E 0 2 0
>> 8:48
>> F 1 8:80 F 1
>
> I was actually asking for "dmsetup status <mirror-device>" rather than
> multipath device. I didn't know that you were using multipath devices!!!
>
> Anyway, looks like you have mpath12 that probably queues I/O on path
> failures rather than failing them back to upper layers. In other words,
> if you were to run "dd" or any other app to mpath12, it would hang too.
>
> mpath12 seems to keep the request and forever wait for the paths to
> become available again in your case. If you really want it to fail,
> configure your multipath accordingly.
>
> Thanks, Malahal.
> PS: "features=1 queue_if_no_path" in your 'multipath -ll' output is the
> source of error here...
>
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> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
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