Re: good dm-mpath test setup?

[Hannes Reinecke <hare@suse.de>]

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On 06/05/2014 01:50 PM, Christoph Hellwig wrote:
> I've been looking into support blk-mq/scsi-mq in dm-mpath, but I'm
> already running into issues with mainline.  I created a couple luns
> (without second path) using iet, and then using the iscsi initiator
> to access them.  But it seems like no I/O is possible through dm-mpath
> for this simple setup as the kpartx processes spawned by udev already
> hang.  Is dm-mpath (default config, no multipath.conf) support to work
> for a single path setup, or is this expected behavior?
>
Hmm. This shouldn't happen.

But be aware, that multipath doesn't play well together with systemd 
currently.
I've done plenty of fixes to get it up and running for SLES12; once 
they've stabilized I'll be sending them mainline.

But for a stable testbed I would recommend against systemd currently.

> Does anyone have a good default iet or maybe lio config for dm-mpath
> testing?
>
The easiest bit would be set set up lio in loopback mode, and map 
two luns pointing to the same device.

I've attached a small script I'm using for a quick test here.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)

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