StorCase Technology SCSI-to-SCSI Single RAID - Manual (Page 53)

DXIFS-160/RAID User's Guide - Rev. B00 StorCase Technology, Inc.
Configuration 43
However, the controller permits writeback cache settings to be changed on a member drive
of a fault-tolerant array, because it can remove the drive from the array to perform the
operation. The following steps summarize how the controller handles disk writeback cache
changes:
1. The recommended method to change an individual drive's writeback cache settings
is to issue the command to available (nonmember drives); it also works safely on
dedicated spares and pool spares.
2. On fault-tolerant arrays, the controller automatically issues a "down drive" command
to remove the drive from the array. The array state becomes critical and the controller
starts a reconstruct, if possible, using an available dedicated or appropriately-sized
pool spare. Using this method to change a drive's writeback cache setting is not
recommended!
3. The Change Writeback Cache command fails on a critical or reconstructing array.
4. The Change Writeback Cache command fails on any RAID 0 array or Volume Set
members, because these arrays are not fault-tolerant.
Any disk drives with writeback cache enabled should be connected to an Uninterruptable
Power Supply (UPS) in case of power failure. If the drives are not on a UPS and power is
lost during disk writes, the RAID system will lose any data in the disk's writeback cache that
has been committed by the controller.
Event Log Menu
This command allows the user to view the Event Log one entry at a time. Press Ctrl-E on the
terminal to view a full screen Event Log.
Refer to section "Event Logs" in Appendix C -Troubleshooting for further information.
Shutdown/Restart
This command shuts down the controller. After the shutdown is complete, press Enter to
restart. This ensures that the writeback cache has been flushed to the disk (as opposed to
just turning off the power without issuing the shutdown command).