[dm-devel] Wrong behaviour of multipathing on Active/Passive storage array
Mikhail Shevyakov
Shevyakov.M at avroraid.com
Mon Jul 11 15:34:46 UTC 2011
Hello!
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/dm-devel/attachments/20110711/8264adaf/attachment.htm>
More information about the dm-devel
mailing list