User`s manual

Chapter M - GDT User's Manual

The verification may take quite a long time, but you can terminate it by pres sing <ESC>.

M.8.1.6 Notes on the configuration of RAID 4/5 host drives

(1) Preferably, use host drives of the type

disk

to build an array drive.

Of course, RAID 4 and RAID 5 disk arrays can be configured with host drives of the types

chain and mirror, too, but the aspects of security (chain) and cost (mirror) should be taken into

consideration as well. For regular RAID 4 and RAID 5 disk arrays, type disk host drives are

used.

(2) The host drives of an array drive should have the same storage capacity.

In order not to waste valuable storage capacity, for an array drive you should only use host

drives that have the same storage capacity.

E.g. Host drive 0 200MB

Host drive 1 200MB

Host drive 2 200MB

Host drive 3 200MB

This disk array has a usable storage capacity of 600MB.

And NOT Host drive 0 150MB

Host drive 1 100MB

Host drive 2 200MB

Host drive 3 200MB

This disk array has only 300MB of usable storage capacity !

(3) Use different SCSI channels when setting up cache drives for disk arrays.

Alternate between SCSI channels A and B (and C, D, and E if available) when setting up

SCSI devices for cache drives. This configuration method has a considerable impact on a

disk array's performance. Always keep in mind that the data is written in stripes to the