SSY-V: disconnected mirror links

Recently I got warning emails from one of our DataCore SSY-V installations regarding broken mirror pathes and thus many vDisks in "log recovery pending" state.

This installation uses four uni-directional mirror pathes (mirror pathes where the used fc ports work either in Initiator or Target mode and not both at the same time).

I checked the installation and saw that the two pathes where DCS2 was the initiator and DCS1 was the target we shown as logged out/disconnected.

I checked the trace logs but all I found were many!!! aborts, timeouts and disconnects but nothing really told me why this happened. All I was able to identify was that the initiator on DCS2 seemed to be the problem. It was shown as logged out on DCS1 but link was shown as up.

Rescaning ports on both DCS didn't help and rebooting DCS2 was not an option since this server was the DCS that held the latest vDisk state. So rebooting that server would cause all systems to go down that have out-of-sync vDisks connected.

So the only option we had was to manually force the FC HBA to reinitialize. But how to do? The mirror pathes are in a direct-attached loop so we could plug out the FC cable but this only resets the link not the initator itself. If this problem is caused by a driver issue, this wouldn't really help.

So we decided to force the reset by changing the connection mode in the mirror port properties in SSY-V GUI. It was set to default, so we changed to point-to-point mode... nothing happened. So we switched back to default mode and suddently the initiator was able to reconnect to the target port and the mirror path was back online.

VDisk sync was started immediately and after all disks were up-to-date again we did the same for the second path.

We opened a case at DataCore's technical support and they told us, this is a known bug and engineering is working on it but currently there is no solution available.

So all you can do is using the workaround mentioned above and hoping that this only affects some of your mirror pathes and not all at the same time. I can't estimate the real risk for that issue. We have only a single installation being affected by this at the moment and this installation is the only one with uni-directional mirror pathes. Perhaps this won't even occur on a bidirectional mirror setup.

Hope, DataCore will release a patch for this problem soon. FYI, even with latest PSP1 for SSY-V9 this bug is still unresolved.

 

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