I try to configure multipathing for Active/Passive storage and I have a problem with this:
when paths are switched (Active->Passive, Passive->Active) all read/write operations
are suspended. When paths switches back read/write resumes.
Following is the configuration:
# less /etc/multipath.conf
defaults { user_friendly_names yes prio alua path_checker tur no_path_retry 10 fast_io_fail_tmo 5 polling_interval 10 selector "round-robin 0" path_grouping_policy multibus rr_min_io 100 failback immediate }
# multipath -ll mpathb (0AvroRAIDDVAS 000000000000000097f62ae1) dm-0 AvroRAID,DVAS size=683G features='1 queue_if_no_path' hwhandler='0' wp=rw `-+- policy='round-robin 0' prio=5 status=active |- 7:0:0:0 sdc 8:32 active ghost running `- 9:0:0:0 sdd 8:48 active ready running This is output of st_turs: # sg_turs -v /dev/sdd test unit ready cdb: 00 00 00 00 00 00 # sg_turs -v /dev/sdc test unit ready cdb: 00 00 00 00 00 00 test unit ready: Fixed format, current; Sense key: Not Ready Additional sense: Logical unit not accessible, target port in standby state Info fld=0x0 [0] device not ready And REPORT TARGET PORT GROUPS output: #sg_rtpg /dev/sdd Report target port groups: target port group id : 0x1 , Pref=1 target port group asymmetric access state : 0x00 T_SUP : 0, O_SUP : 0, U_SUP : 1, S_SUP : 1, AN_SUP : 0, AO_SUP : 1 status code : 0x02 vendor unique status : 0x00 target port count : 02 Relative target port ids: 0x01 0x02 #sg_rtpg /dev/sdc Report target port groups: target port group id : 0x2 , Pref=0 target port group asymmetric access state : 0x02 T_SUP : 0, O_SUP : 0, U_SUP : 1, S_SUP : 1, AN_SUP : 0, AO_SUP : 1 status code : 0x02 vendor unique status : 0x00 target port count : 04 Relative target port ids: 0x01 0x02 0x03 0x04 I used dd to write on the dm device: #dd if=/dev/zero of=/dev/dm-0 oflag=direct bs=1M Everything works fine untill paths are switched. dd stops, turs output: # sg_turs -v /dev/sdd test unit ready cdb: 00 00 00 00 00 00 # sg_turs -v /dev/sdc test unit ready cdb: 00 00 00 00 00 00 test unit ready: Fixed format, current; Sense key: Not Ready Additional sense: Logical unit not accessible, target port in standby state Info fld=0x0 [0] device not ready REPORT TARGET PORT GROUPS output: # sg_rtpg /dev/sdd Report target port groups: target port group id : 0x1 , Pref=0 target port group asymmetric access state : 0x02 T_SUP : 0, O_SUP : 0, U_SUP : 1, S_SUP : 1, AN_SUP : 0, AO_SUP : 1 status code : 0x02 vendor unique status : 0x00 target port count : 02 Relative target port ids: 0x01 0x02 # sg_rtpg /dev/sdc Report target port groups: target port group id : 0x2 , Pref=1 target port group asymmetric access state : 0x00 T_SUP : 0, O_SUP : 0, U_SUP : 1, S_SUP : 1, AN_SUP : 0, AO_SUP : 1 status code : 0x02 vendor unique status : 0x00 target port count : 04 Relative target port ids: 0x01 0x02 0x03 0x04 As you can see paths' states are switched.Output of multipath: # multipath -ll mpathb (0AvroRAIDDVAS 000000000000000097f62ae1) dm-0 AvroRAID,DVAS size=683G features='1 queue_if_no_path' hwhandler='0' wp=rw `-+- policy='round-robin 0' prio=5 status=enabled |- 7:0:0:0 sdc 8:32 failed ready running `- 9:0:0:0 sdd 8:48 failed ghost running So states of the paths are changed but multipath for some reason fails both paths. Is something wrong with my config or is it a bug in multipath? Could you help me with this problem? Regards Mikhail Shevyakov
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