Compaq 3200 - Manual (Page 155)

E-13
Compaq Smart Array 3200 Controller Reference Guide
Writer: Rickard Project: Compaq Smart Array 3200 Controller Reference Guide Comments: 340862-002
File Name: L-APPE.DOC Last Saved On: 12/7/98 9:30 AM
COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED
User Selectable Stripe-Size
You can change stripe-size either during the initial configuration of the system,
or later, after the system has been in use for some time. In both cases this must
be performed offline. See Chapter 5 for instructions to set or change stripe-size.
Table E-2 lists the set of valid stripe sizes for each RAID level highlighting the
default values.
Table E-2
Stripe Sizes
Fault-Tolerance
Level
Default (KB) Default (Sectors) Valid Stripe Sizes
(Sectors)
RAID 0 128 ** 256 16, 32, 64, 128,
256*, 512
RAID 1 128 ** 256 16, 32, 64, 128,
256*, 512
RAID 4 16 ** 32 16, 32*, 64, 128
RAID 5 16 ** 32 16, 32*, 64, 128
* Default
** RAID 4 and 5 do not support stripe sizes larger than 64 KB per drive
Because data is re-written to the drives in a different format, the Write cache
must be enabled (batteries charged) to protect the data in the event of power loss
during the change. Also, Array Accelerator memory must be large enough to
support the least common multiple of the two different full stripe sizes. During
an expand/stripe-size change from an 11-drive RAID 5 volume (default, 32
sectors; full stripe = 320 sectors) to a 14-drive RAID 1 volume (default, 256
sectors; full stripe = 1792 sectors), the least common multiple of a full stripe
would require 8960 sectors (4480 KB) available in the Array Accelerator.