HP StorageWorks 1500cs Modular Smart Array - Manual (Page 22)

Modifying an existing configuration 22
• For better system performance, use physical drives that are attached to different ports on the
controller.
• In RAID 5 configurations, keep the risk of logical drive failure low by assigning no more than 14
physical drives to the array.
Each time that you add a physical drive to the array, the configuration view is updated to show how
much free space remains on the array.
4. Click Next when you have finished adding physical drives to the array.
5. If a spare or unassigned physical drive of the appropriate capacity is available, ACU asks you
whether you want to assign a spare drive to the array.
• If you do not want this array to have a spare, click No, and then click Next.
• To assign spare drives to the array, click Yes, and then click Next. On the next screen, select
the drives that you want to assign as spares, and then click Next.
IMPORTANT: Assigning one or more spare drives to an array enables you to postpone replacement of
faulty drives, but it does not increase the fault-tolerance level of any logical drives in the array. For example,
a logical drive in a RAID 5 configuration suffers irretrievable data loss if two physical drives fail
simultaneously, regardless of the number of spare drives assigned to it.
NOTE: An array can have several spares, and any spare can be shared by several arrays.
6. Click through the remaining screens to confirm the configuration.
Create a logical drive
1. Click Create a logical drive, and then click Begin.
2. Select an array that has unused space, and then click Next. (The array must have unused space for
logical drive creation to be possible.)
The screen displays a list of the fault-tolerance levels that are possible for this configuration. For
example, RAID 5 is not listed if the array has only two physical drives.
3. Select a fault-tolerance level, and then click Next.
4. Select a stripe size, and then click Next.
The default stripe size gives optimum performance in a mixed read/write environment. If your system
is used in a different environment, refer to the following table to determine what stripe size to set.
Type of server application Suggested stripe size change
Mixed read/write Accept the default value.
Mainly sequential read (such as
audio/video applications) Use a larger stripe size.
Mainly write (such as image
manipulation applications) Use a smaller stripe size for RAID 5 or
RAID 6 (ADG).
Use a larger stripe size for RAID 0 or
RAID 1+0.
*Not all controllers support RAID 6 (ADG).
The next screen gives you the option to enable MaxBoot. When MaxBoot is enabled, 63 sectors are
used per track instead of 32. This increased number of sectors allows a larger boot partition for
operating systems such as Microsoft® Windows NT® 4.0 that use cylinders, heads, and sectors of a
physical drive to determine the drive size. It also enables you to create a larger logical drive or
increase the logical drive size (extend it) at a later time.
Logical drive performance is likely to decrease with MaxBoot enabled.
5. Decide whether to use MaxBoot, and then click Next.