Administrator Guide

• During system operation, a disk group loses redundancy plus one more disk. For example, three disks are inaccessible in a RAID-6 disk
group or two disks are inaccessible for other fault-tolerant RAID levels. The disk group will be automatically dequarantined if after 60
seconds the disk group status is FTOL, FTDN, or CRIT.
Quarantine isolates the disk group from host access and prevents the system from changing the disk group status to OFFL. The number
of inaccessible disks determines the quarantine status, from least to most severe:
• QTDN (quarantined with a down disk): The RAID-6 disk group has one inaccessible disk. The disk group is fault tolerant but degraded.
If the inaccessible disks come online or if after 60 seconds from being quarantined the disk group is QTCR or QTDN, the disk group is
automatically dequarantined.
• QTCR (quarantined critical): The disk group is critical with at least one inaccessible disk. For example, two disks are inaccessible in a
RAID-6 disk group or one disk is inaccessible for other fault-tolerant RAID levels. If the inaccessible disks come online or if after 60
seconds from being quarantined the disk group is QTCR or QTDN, the disk group is automatically dequarantined.
• QTOF (quarantined offline): The disk group is offline with multiple inaccessible disks causing user data to be incomplete, or is an
NRAID or RAID-0 disk group.
When a disk group is quarantined, its disks become write-locked, its volumes become inaccessible, and it is not available to hosts until it is
dequarantined. If there are interdependencies between the quarantined disk group's volumes and volumes in other disk groups, quarantine
may temporarily impact operation of those other volumes. Depending on the operation, the length of the outage, and the settings
associated with the operation, the operation may automatically resume when the disk group is dequarantined or may require manual
intervention. A disk group can remain quarantined indefinitely without risk of data loss.
A disk group is dequarantined when it is brought back online, which can occur in three ways:
• If the inaccessible disks come online, making the disk group FTOL, the disk group is automatically dequarantined.
• If after 60 seconds from being quarantined the disk group is QTCR or QTDN, the disk group is automatically dequarantined. The
inaccessible disks are marked as failed and the disk group status changes to critical (CRIT) or fault tolerant with a down disk (FTDN).
If the inaccessible disks later come online, they are marked as leftover (LEFTOVR).
• The dequarantine command is used to manually remove a disk group from quarantine. If the inaccessible disks later come online,
they are marked as leftover (LEFTOVR). If event 485 was logged, use the dequarantine command only as specified by the
recommended-action text to help prevent data corruption or loss.
A quarantined disk group can be fully recovered if the inaccessible disks are restored. Make sure that all disks are properly seated, that no
disks have been inadvertently removed, and that no cables have been unplugged. Sometimes not all disks in the disk group power up.
Check that all enclosures have restarted after a power failure. If these problems are found and then fixed, the disk group recovers and no
data is lost.
If the inaccessible disks cannot be restored (for example, they failed), and the disk group's status is FTDN or CRIT, and compatible spares
are available, reconstruction will automatically begin.
If a replacement disk (reconstruct target) is inaccessible at power up, the disk group becomes quarantined. When the disk is found, the
disk group is dequarantined and reconstruction starts. If reconstruction was in process, it continues where it left off.
NOTE:
The only tasks allowed for a quarantined disk group are Dequarantine Disk Group and Remove Disk Groups. If you
delete a quarantined disk group and its inaccessible disks later come online, the disk group will reappear as quarantined
or offline and you must delete it again to clear those disks.
Remove a disk group from quarantine
If specified by the recommended action for event 172 or 485, you can remove a disk group from quarantine.
CAUTION: To help prevent the loss of data, contact technical support before removing a disk group from quarantine.
1. In the Pools topic, select the quarantined disk group.
2. Select Action > Dequarantine Disk Group.
The Dequarantine Disk Group panel opens.
3. Click OK.
Depending on the number of disks that remain active in the disk group, its health might change to Degraded (RAID 6 only) and its
status changes to FTOL, CRIT, or FTDN. For status descriptions, see Related Disk Groups table.
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Working in the Pools topic