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elizada
23-May-2013, 15:58
Hi,

I installed Boot from SAN (FC) SLES 11 SP2 using GUI.
The default multipath configuration seems not good because each path group contains just only one path and round-robin configuration doesn't really apply between all paths. :confused:
This configuration is the default OS configuration and I didn't change a thing after.

What I get by default
======================
mpatha (xxxxxxxxxxxxxxxx) dm-0 XXX,XXXXXX
size=48G features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=1 status=active
| `- 0:0:4:1 sdc 8:32 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 0:0:5:1 sdd 8:48 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 1:0:3:1 sdh 8:112 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 1:0:5:1 sdi 8:128 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 0:0:7:1 sde 8:64 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 0:0:3:1 sdb 8:16 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 1:0:7:1 sdj 8:144 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 1:0:2:1 sdg 8:96 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 1:0:0:1 sdf 8:80 active ready running
`-+- policy='round-robin 0' prio=1 status=enabled
`- 0:0:1:1 sda 8:0 active ready running

What I think I should get
==========================
mpatha (xxxxxxxxxxxxxxxx) dm-0 XXX,XXXXXX
size=48G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
|- 0:0:4:1 sdc 8:32 active ready running
|- 0:0:5:1 sdd 8:48 active ready running
|- 1:0:3:1 sdh 8:112 active ready running
|- 1:0:5:1 sdi 8:128 active ready running
|- 0:0:7:1 sde 8:64 active ready running
|- 0:0:3:1 sdb 8:16 active ready running
|- 1:0:7:1 sdj 8:144 active ready running
|- 1:0:2:1 sdg 8:96 active ready running
|- 1:0:0:1 sdf 8:80 active ready running
`- 0:0:1:1 sda 8:0 active ready running

Magic31
23-May-2013, 17:19
Hi,

I installed Boot from SAN (FC) SLES 11 SP2 using GUI.
The default multipath configuration seems not good...

Which SAN do you have attached specifically (Make & model number)?

Also, how many paths are there from server to SAN? I'm surprised to see that many paths for one device.

Cheers,
Willem

elizada
30-May-2013, 08:35
Hi,

I'm using XIV storage controller, model 2810
XIV works as grid and it's recommended to zone your host with many as possible interfaces, so this why you can see so many paths

Magic31
30-May-2013, 16:01
Hi,

I'm using XIV storage controller, model 2810
XIV works as grid and it's recommended to zone your host with many as possible interfaces, so this why you can see so many paths

Hi Elizada,

Thanks for the info. I don't have personal experience with this SAN, but it could have to do with how you have set the devices section for this SAN in /etc/multipath.conf.

From the settings I normally do for our SANS + this link : http://pic.dhe.ibm.com/infocenter/strhosts/ic/topic/com.ibm.help.strghosts.doc/HAK/1.8.0/HAG/hak_ug_ch8_multipath_config.html

Maybe these settings would get you the right results (use with care):



devices {
device {
vendor "IBM"
product "2810XIV"
path_selector "round-robin 0"
#or try#path_selector "queue-length 0"
path_grouping_policy multibus
rr_min_io 15
rr_weight priorities
features "1 no_partitions"
path_checker tur
failback 15
no_path_retry queue
no_path_retry 5
features "0"
polling_interval 3
}



Posting your current multipath.conf (in total) could shed some light on why you are seeing what you are seeing.

Cheers,
Willem