Compaq 3200 manual User Selectable Stripe-Size, Table E-2 Stripe Sizes, E-13

E-13

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		Default (KB)		Default (Sectors)		Valid Stripe Sizes
Level						(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.

Compaq Smart Array 3200 Controller Reference Guide