Multipath and iSCSI on 11.10

[Peter M. Petrakis]

On 12/23/2011 09:07 PM, Albert Chin wrote:
> On Fri, Dec 23, 2011 at 07:20:01PM -0600, Albert Chin wrote:
>> I have device-mapper-multipath configured with iSCSI. I have two
>> interfaces configured to communicate with the iSCSI server. I discover
>> and connect with the iSCSI targets as follows:
>>   (1) # iscsiadm -m discovery -t st -p 10.191.61.1:3260 -I iface1 -P 1
>>   (2) # iscsiadm -m discovery -t st -p 10.191.62.1:3260 -I iface2 -P 1
>>   (3) # iscsiadm -m node -p 10.191.61.1:3260 -I iface1 -l
>>   (4) # iscsiadm -m node -p 10.191.62.1:3260 -I iface2 -l
>>   # cat /etc/multipath.conf
>>   defaults {
>>     selector             "round-robin 0"
>>     udev_dir             /dev
>>     user_friendly_names  yes
>>   }
>>   [[ snip snip ]]
>>   # multipath -ll
>>   winry (3600144f057774b0000004eeab58a0001) dm-24 OI,COMSTAR
>>   size=500G features='0' hwhandler='0' wp=rw
>>   |-+- policy='round-robin 0' prio=1 status=active
>>   | `- 12:0:0:0 sdd  8:48   active ready running
>>   `-+- policy='round-robin 0' prio=1 status=enabled
>>     `- 41:0:0:0 sdae 65:224 active ready running
>>   sai (3600144f057774b0000004ebf539e001d) dm-9 OI,COMSTAR
>>   size=500G features='0' hwhandler='0' wp=rw
>>   |-+- policy='round-robin 0' prio=1 status=active
>>   | `- 17:0:0:0 sdv  65:80  active ready running
>>   `-+- policy='round-robin 0' prio=1 status=enabled
>>     `- 54:0:0:0 sdai 66:32  active ready running
>>   ...
>>
>> 1. Based on the above multipath -ll output, it seems that I am not
>>    load-balancing across both NICs. Why not? 
> 
> Adding path_grouping_policy multibus fixed this.

Interesting, multibus is supposed to be the default policy...
 
>> 2. When I boot the system, the initiator does not log in to any
>>    target. Therefore, I need to rerun (3) and (4) above. Why?
> 
> Still not sure about this one.

This is to be configured outside of multipath. You'll need to configure
the iscsid initiator config file to login into these targets at boot.

apt-get install open-iscsi
vi /etc/iscsi/iscsid.conf

Peter