Over the past little while I have seen my cluster volumes deactivate overnight for some reason. The last couple of times it happened I get the following types of messages in the log. The volumes don't fail over, they just dismount. iManager shows the cluster resource as 'running' but browsing the mapped volume it appears empty. I can take the cluster resource offline (or fail it over) and then back online and all is well again. This seems to happen at night during a time of little load on the servers. Not sure what else to check.

Aug 18 20:07:04 boes1 kernel: sd 1:0:0:0: SCSI error: return code = 0x00000018
Aug 18 20:07:04 boes1 kernel: end_request: I/O error, dev sdb, sector 2200
Aug 18 20:07:04 boes1 kernel: BIO_UPTODATE not set. Got an IO error
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [Error] zlssMSAP.c[538]
Aug 18 20:07:04 boes1 kernel: Aug 18, 2011 8:07:04 pm NSS<ZLSS>-4.13a-xxxx:
Aug 18 20:07:04 boes1 kernel: MSAP: Pool "CVOL1" read error 20204.
Aug 18 20:07:04 boes1 kernel:
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [MSAP] comnLog.c[201]
Aug 18 20:07:04 boes1 kernel: Pool "CVOL1" - Read error(20204).
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [Error] comnPool.c[2575]
Aug 18 20:07:04 boes1 kernel: Aug 18, 2011 8:07:04 pm NSS<COMN>-4.13a-xxxx:
Aug 18 20:07:04 boes1 kernel: Pool CVOL1: System data I/O error 20204(zlssMSAP.c[1812]).
Aug 18 20:07:04 boes1 kernel: Block 0(file block 0)(ZID 0)
Aug 18 20:07:04 boes1 kernel: klogd 1.4.1, ---------- state change ----------
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [Error] zfsVolumeData.c[218]
Aug 18 20:07:04 boes1 kernel: Aug 18, 2011 8:07:04 pm NSS<ZLSS>-4.13a-1449:
Aug 18 20:07:04 boes1 kernel: Error reading VolumeData Block 36, status=20206.
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [Error] zfsVolumeData.c[218]
Aug 18 20:07:04 boes1 kernel: Aug 18, 2011 8:07:04 pm NSS<ZLSS>-4.13a-1449:
Aug 18 20:07:04 boes1 kernel: Error reading VolumeData Block 26213763, status=20206.
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [Error] zlssLogicalVolume.c[4991]
Aug 18 20:07:04 boes1 kernel: Aug 18, 2011 8:07:04 pm NSS<ZLSS>-4.13a-1449:
Aug 18 20:07:04 boes1 kernel: Error reading PoolData Block 26213766, status=20206.
Aug 18 20:07:04 boes1 kernel: NSSLOG ==> [Error] zfsVolumeData.c[218]