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Old 11-19-2007, 04:16 PM
"Scott Moseman"
 
Default [dm-devel] Failing on NIC removal

So I finally got my multipath running through both the NIC and HBA
interfaces, but I'm not having any luck going through testing to
verify it's actually failing over between the connections.

# multipath -l
mpath0 (30690a018f015191a6472441d1500f057)
[size=4 GB][features="0"][hwhandler="0"]
\_ round-robin 0 [active]
\_ 3:0:0:0 sdc 8:32 [active][ready]
\_ round-robin 0 [enabled]
\_ 1:0:1:0 sdb 8:16 [active][ready]

I can unplug the HBA (see below) and the connection to the SAN remains.

# multipath -l
mpath0 (30690a018f015191a6472441d1500f057)
[size=4 GB][features="0"][hwhandler="0"]
\_ round-robin 0 [active]
\_ 3:0:0:0 sdc 8:32 [active][ready]
\_ round-robin 0 [enabled]
\_ 1:0:1:0 sdb 8:16 [failed][faulty]

But when I unplug the NIC connection, the multipath command hands,
trying to list files on the SAN partition hangs, and I'm getting these
messages:

Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: Connect failed with rc
-113: No route to host
Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: establish_session
failed. Could not connect to target
Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: Waiting 10 seconds
before next login attempt

How to troubleshoot this situation?

Thanks,
Scott

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Old 11-19-2007, 08:46 PM
Mike Anderson
 
Default [dm-devel] Failing on NIC removal

cc'ing open-iscsi

Scott Moseman <scmoseman@gmail.com> wrote:
> So I finally got my multipath running through both the NIC and HBA
> interfaces, but I'm not having any luck going through testing to
> verify it's actually failing over between the connections.
>
> # multipath -l
> mpath0 (30690a018f015191a6472441d1500f057)
> [size=4 GB][features="0"][hwhandler="0"]
> \_ round-robin 0 [active]
> \_ 3:0:0:0 sdc 8:32 [active][ready]
> \_ round-robin 0 [enabled]
> \_ 1:0:1:0 sdb 8:16 [active][ready]
>
> I can unplug the HBA (see below) and the connection to the SAN remains.
>
> # multipath -l
> mpath0 (30690a018f015191a6472441d1500f057)
> [size=4 GB][features="0"][hwhandler="0"]
> \_ round-robin 0 [active]
> \_ 3:0:0:0 sdc 8:32 [active][ready]
> \_ round-robin 0 [enabled]
> \_ 1:0:1:0 sdb 8:16 [failed][faulty]
>
> But when I unplug the NIC connection, the multipath command hands,
> trying to list files on the SAN partition hangs, and I'm getting these
> messages:
>
> Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: Connect failed with rc
> -113: No route to host
> Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: establish_session
> failed. Could not connect to target
> Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: Waiting 10 seconds
> before next login attempt
>
> How to troubleshoot this situation?

The IO is hanging waiting for the connection to be reestablished.

You may need to set ConnFailTimeout to a non-zero value as indicated in
http://people.redhat.com/mchristi/iscsi/RHEL4/doc/readme

Someone on the open-iscsi list may have a better suggestion.

-andmike
--
Michael Anderson
andmike@linux.vnet.ibm.com

--
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https://www.redhat.com/mailman/listinfo/dm-devel
 
Old 11-19-2007, 08:58 PM
Mike Christie
 
Default [dm-devel] Failing on NIC removal

Mike Anderson wrote:

cc'ing open-iscsi

Scott Moseman <scmoseman@gmail.com> wrote:

So I finally got my multipath running through both the NIC and HBA
interfaces, but I'm not having any luck going through testing to
verify it's actually failing over between the connections.

# multipath -l
mpath0 (30690a018f015191a6472441d1500f057)
[size=4 GB][features="0"][hwhandler="0"]
\_ round-robin 0 [active]
\_ 3:0:0:0 sdc 8:32 [active][ready]
\_ round-robin 0 [enabled]
\_ 1:0:1:0 sdb 8:16 [active][ready]

I can unplug the HBA (see below) and the connection to the SAN remains.

# multipath -l
mpath0 (30690a018f015191a6472441d1500f057)
[size=4 GB][features="0"][hwhandler="0"]
\_ round-robin 0 [active]
\_ 3:0:0:0 sdc 8:32 [active][ready]
\_ round-robin 0 [enabled]
\_ 1:0:1:0 sdb 8:16 [failed][faulty]

But when I unplug the NIC connection, the multipath command hands,
trying to list files on the SAN partition hangs, and I'm getting these
messages:

Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: Connect failed with rc
-113: No route to host
Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: establish_session
failed. Could not connect to target
Nov 19 17:15:13 ems1 kernel: iscsi-sfnet:host3: Waiting 10 seconds
before next login attempt

How to troubleshoot this situation?


The IO is hanging waiting for the connection to be reestablished.


You may need to set ConnFailTimeout to a non-zero value as indicated in
http://people.redhat.com/mchristi/iscsi/RHEL4/doc/readme



Mike Anderson is right. If you are using multipath you should set
ConnFailTimeout to a low value like 3 or 5 seconds, because we want to
fail commands quickly to the multipath layer. For dm-multipath you want
to then set no_path_retry to either queue IO forever (or until the paths
come back), or to some timeout.


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Old 11-20-2007, 01:16 PM
"Scott Moseman"
 
Default [dm-devel] Failing on NIC removal

On Nov 19, 2007 3:46 PM, Mike Anderson <andmike@linux.vnet.ibm.com> wrote:
>
> You may need to set ConnFailTimeout to a non-zero value as indicated in
> http://people.redhat.com/mchristi/iscsi/RHEL4/doc/readme
>

Hey Mike,

Sweet, my failover is working perfect now!

Thanks for the help!
Scott

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dm-devel@redhat.com
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