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Re: [dm-devel] no_path_retry configurable per device basis?



ok.
Ach, I missed the "devices" section....
So now my multipath.conf is

blacklist {
        devnode "^cciss!c[0-9]d[0-9]*"
}

defaults {
	user_friendly_names yes
	polling_interval 30
	rr_min_io 100
        no_path_retry queue
}

devices {
	device {
		vendor			"IBM"
		product			"1750500"
		getuid_callout		"/sbin/scsi_id -g -u -s /block/%n"
                prio_callout            "/sbin/mpath_prio_alua %d"	
		features		"0"
		hardware_handler	"0"
                path_grouping_policy    group_by_prio
		failback		immediate
		rr_weight		uniform
                path_checker            tur
	  }
}

multipaths {
	multipath {
		wwid			3600507630efe0b0c0000000000000600
		alias			mpath0
	}
[snip]
	multipath {
		wwid			3600507630efe0b0c0000000000000610
		alias			mpath6
                no_path_retry           2
	}
[snip]
}

And after running
multipath
and reboot I get this with
multipath -l

so it seems it remains in "features=1 queue_if_no_path" from the
controller point of view....

[root orastud2 ~]# multipath -l
[snip]
mpath0 (3600507630efe0b0c0000000000000600) dm-0 IBM,1750500
[size=60G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
 \_ 0:0:1:0  sdaa 65:160 [active][undef]
 \_ 1:0:1:0  sdab 65:176 [active][undef]
\_ round-robin 0 [prio=0][enabled]
 \_ 0:0:0:0  sda  8:0    [active][undef]
 \_ 1:0:0:0  sdd  8:48   [active][undef]
[snip]
mpath6 (3600507630efe0b0c0000000000000610) dm-12 IBM,1750500
[size=1.0G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
 \_ 0:0:1:12 sday 67:32  [active][undef]
 \_ 1:0:1:12 sdaz 67:48  [active][undef]
\_ round-robin 0 [prio=0][enabled]
 \_ 1:0:0:12 sdy  65:128 [active][undef]
 \_ 0:0:0:12 sdz  65:144 [active][undef]
[snip]

Can I consider it ok?
I see with
multipath -l -v 3
...
     1:0:0:12 sdy  65:128 0   [undef][undef] IBM,1750500
     0:0:0:12 sdz  65:144 0   [undef][undef] IBM,1750500
params = 1 queue_if_no_path 0 2 1 round-robin 0 2 1 66:32 100 66:48 100 round-ro
bin 0 2 1 8:128 100 8:144 100
status = 2 0 0 0 2 1 A 0 2 0 66:32 A 0 66:48 A 0 E 0 2 0 8:128 A 0 8:144 A 0
mpath2 (3600507630efe0b0c0000000000000602) dm-4 IBM,1750500
[size=15G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
 \_ 1:0:1:4  sdai 66:32  [active][undef]
 \_ 0:0:1:4  sdaj 66:48  [active][undef]
\_ round-robin 0 [prio=0][enabled]
 \_ 0:0:0:4  sdi  8:128  [active][undef]
 \_ 1:0:0:4  sdj  8:144  [active][undef]
...
params = 1 queue_if_no_path 0 2 1 round-robin 0 2 1 67:32 100 67:48 100 round-ro
bin 0 2 1 65:128 100 65:144 100
status = 2 0 0 0 2 1 A 0 2 0 67:32 A 0 67:48 A 0 E 0 2 0 65:128 A 0 65:144 A 0
mpath6 (3600507630efe0b0c0000000000000610) dm-12 IBM,1750500
[size=1.0G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
 \_ 0:0:1:12 sday 67:32  [active][undef]
 \_ 1:0:1:12 sdaz 67:48  [active][undef]
\_ round-robin 0 [prio=0][enabled]
 \_ 1:0:0:12 sdy  65:128 [active][undef]
 \_ 0:0:0:12 sdz  65:144 [active][undef]

So it seems there is no difference between mpath6 an the other ones??????

btw: if I change multipath.conf and I do nothing but reboot, I will
get the new config, correct?
This because, in my case, in rc.sysinit I have the block
        if ! strstr "$cmdline" nompath && [ -f /etc/multipath.conf -a \
                        -x /sbin/multipath.static ]; then
                modprobe dm-multipath > /dev/null 2>&1
                /sbin/multipath.static -v 0
                if [ -x /sbin/kpartx ]; then
                        /sbin/dmsetup ls --target multipath --exec
"/sbin/kpartx -a -p p"
                fi

that executes the
/sbin/multipath.static
command.
Is this correct?
And in general could I change in any way the multipath.conf and then run the
multipath
command or are there any parameters that need reboot?

Thanks for all your help.

Gianluca

On Wed, May 13, 2009 at 8:08 PM, Bryn M. Reeves <bmr redhat com> wrote:
> 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.
>
>
> --
> dm-devel mailing list
> dm-devel redhat com
> https://www.redhat.com/mailman/listinfo/dm-devel
>


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