On Wed, 2009-05-13 at 19:35 +0200, Gianluca Cecchi wrote:
> Thanks for answering.
> why will I still see queue if_if_no_path?
Because that's how retries are implemented; we enable queuing in the
device-mapper target and setup a counter. Every time the I/O fails we
decrement the counter by one. When it hits zero queuing is disabled in
the kernel and the queued I/Os are permitted to fail. This is different
to "no_path_retry queue" or "features '1 queue_if_no_path'" because with
those options queuing will never be disabled. We keep the I/O in memory
indefinitely until the paths return (or the host is rebooted).
> Ok for the kb... it was the same I referred to in my qyestion... ;-)
Sorry, didn't spot that ;)
> And what about having a multipath.conf like this?
>
> blacklist {
> devnode "^cciss!c[0-9]d[0-9]*"
> }
>
I'd put "no_path_retry queue" in your defaults block since you want it
for all but one device on this storage:
> defaults {
> user_friendly_names yes
> polling_interval 30
> rr_min_io 100
> }
The device section must be inside a devices { /*...*/ } block or it
won't get parsed/recognised:
> device {
> vendor "IBM"
> product "1750500"
> getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
> prio_callout "/sbin/mpath_prio_alua %d"
> hardware_handler "0"
> path_grouping_policy group_by_prio
> failback immediate
> rr_weight uniform
> path_checker tur
Since you only want this behavior for one LUN, why not set it at the
multipath level?
> no_path_retry 3
> }
> multipaths {
> multipath {
> wwid 3600507630efe0b0c0000000000000600
> alias mpath0
You can probably put this line in your defaults block and only override
it for the LUN on which you want a max of three retries:
> no_path_retry queue
> }
> multipath {
> wwid 3600507630efe0b0c0000000000000601
> alias mpath1
> no_path_retry queue
> }
> [snip]
> multipath {
I'd probably put the "no_path_retry 3" here:
> wwid 3600507630efe0b0c0000000000000610
> alias mpath6
> }
> [snip]
> }
>
> what would I see with multipath -l?
>
> As in defaults for this device there is
> features 1 queue_if_no_path
> and there is no other option configurable per "features" key in device
> section....
> what would be the effect?
> Or in other words, can I disable the "features" key for a device....?
> For example setting fir it the no_path_retry that semms applicable to
> the device section itself...?
You'll need to remove that features option from the device block as you
have above, or specify an empty features property like:
features "0"
Regards,
Bryn.
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