SafeStor/FT II, Appendix E - Using Cubix RAID Products

Appendix E
Using Cubix RAID Products

If using Cubix SafeStor-FT II products with SCSI RAID controller cards, read the following sections for important information affecting system setup and operation.

Swapping Drives in a RAID Array

Cubix requires halting SCSI bus traffic when swapping SCSI drives. Removing and inserting drives while there is drive activity often causes "glitches" on the SCSI net which can cause controller cards and SCSI drives to function improperly. Even "glitchless" connectors and other protective SCSI hardware are not fool proof when used this way.

Furthermore, many SCSI drives are very sensitive to being moved while they are spinning down. In order to minimize risk to drive media, the removal of group power and a full spin down period (normally ten seconds) are advised when removing drives.

From a network standpoint, the most efficient way to quiet SCSI activity for a disk swap is to issue a "SCSI Quiet Bus" command via the RAID Controller software, or if that is not convenient, for the network manager to issue a bulletin that the server will be off-line for a specified time, then dismount the volume. Note that using one or more "hot spare" drives is an essential way to maintain fault tolerance until a convenient time arises to halt the SCSI traffic for a disk swap.

DPT Storage Manager Notes

The Quiet SCSI Bus feature is currently available only under DOS, Windows, and Novell NetWare. It is not available for Windows NT. (See previous section.)

The INSTALL.BAT program is used to load the Storage Manager and do the initial system initialization. INSTALL.BAT uses the ("DPTMGR/INSTALL") switch and should be used only during initial installations. For subsequent loading of the Storage Manager, use the ("DPTMGR") command alone.

Avoid reboot or power down of the system while low-level format of hard drive(s) is in progress.

While the default RAID -5 stripe size may come up as 8 KB, use the override value of 128 KB stripes when building array.

DPT Novell NetWare User Notes

If you are using NetWare 4.x and workstation VLM's, avoid interrupt level IRQ 15 for DPT controllers in the server. In general, try a different interrupt level than IRQ 15 if any error messages describing "lost interrupts" are encountered.
If using NetWare duplexing, use an interrupt other than IRQ 15 for the DPT controllers in the server.
DPT NetWare drivers do not support mixing DPT ISA, EISA, or PCI controller cards in a single system.
In a RAID system with a hot spare, the spare drive will replace a failed drive with the message "Array Dead: Multiple Drive Failure." This message shows that the swap has taken place, and is not to be interpreted as anything more.

SCSI Drive Notes

In RAID arrays, Cubix baselines all SCSI drives with respect to error correction, cache policy, etc. This drive setup is done prior to running any RAID software, and is important in maintaining consistent RAID array behavior in the field.