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Hi, In the process of testing path failover I
noticed the following: a) when the path is made
unavailable(/dev/sdd) for a logical device “mp1” on a
multipath target, the status of the path becomes [faulty][active]
mp1 [size=1 GB][features="0"][hwhandler="0"] \_ round-robin 0 [enabled] \_ 0:0:0:1 sda
8:0 [ready][active] \_ round-robin 0
[active][first] \_ 1:0:0:1 sdd
8:48 [faulty ][active] b) When an dd is executed on
/dev/mapper/mp1, the state of the paths is as follows
mp1 [size=1
GB][features="0"][hwhandler="0"] \_ round-robin 0
[active][first] \_ 0:0:0:1 sda
8:0 [ready][active] \_ round-robin 0 [enabled] \_ 1:0:0:1 sdd
8:48 [faulty ][failed] b) Now if the path is made available for the
same logical device (/dev/sdd), the status is as follows
mp1 [size=1
GB][features="0"][hwhandler="0"] \_ round-robin 0
[active][first] \_ 0:0:0:1 sda
8:0 [ready][active] \_ round-robin 0 [enabled] \_ 1:0:0:1 sdd
8:48 [ready ][failed] Note the path /dev/sdd has become
[ready][failed] not [ready][active]. Now if path /dev/sda is made unavailable,
then if “dd” is run on /dev/mapper/mp1, it returns with
input/output error, as none of the path will be in [ready][active] state. The following
is the state now:
mp1 [size=1
GB][features="0"][hwhandler="0"] \_ round-robin 0
[active][first] \_ 0:0:0:1 sda
8:0 [faulty]][active] \_ round-robin 0 [enabled] \_ 1:0:0:1 sdd
8:48 [ready ][failed] Kindly explain me what the two states for
each path infer. Like [ready][active] or [faulty][active] or [faulty][failed]
or [ready][failed]. Also let me know how to failover to other path (/dev/sdd)
as it shows [ready][failed] status. If I execute just “multipath”
tool from the command prompt the states get updated properly as
mp1 [size=1
GB][features="0"][hwhandler="0"] \_ round-robin 0
[active][first] \_ 0:0:0:1 sda
8:0 [faulty]][active] \_ round-robin 0 [enabled] \_ 1:0:0:1 sdd
8:48 [ready ][active] After this I will be able to do IO using
“dd”. I suspect that I haven’t configured my hotplug to
call “multipath” tool as the path is made available/unavailable.
I am not sure on where I get hotplug script for multipath and how to
configure hotplug for calling the “multipath” tool. I appreciate if
anyone can help me out in this regard. Thanks and regards Murthy |
