HP Surestore Disk Array 12h and FC60 - Manual (Page 244)

244 Managing Disk Array Capacity
Selecting disks in the incorrect order of 1:2, 2:2, 1:3, and 2:3 results in mirrored pairs of
1:2/1:3 and 2:2/2:3. This puts the primary disk and mirror disk of each pair in the same
enclosure, making the LUN vulnerable to an enclosure failure.
Figure 85 Disk Selection for a RAID 0/1 LUN
How are disk modules in the array identified?
When performing tasks such as binding LUNs , disk modules are identified by a numbered
pair of the form “channel number:SCSI ID”. For example, 1:3 identifies the disk module on
channel 1 with a SCSI ID of 3. Status information may also include the enclosure number
and slot number.
• Channel number indicates the SCSI channel that the disk enclosure containing the
disk module is connected to. There are six channels available (1 - 6). If the disk
enclosure is using full-bus configuration, all disk modules within the enclosure will be
on the same SCSI channel. If the disk enclosure is configured for split-bus operation,
disks in the even-numbered slots will be on one channel, and disks in the odd-numbered
slots will be on a different channel.
• SCSI ID identifies the ID assigned to the disk module. SCSI ID’s are determined by the
slot in which the disk module is installed in the disk enclosure. If the disk enclosure is
using full-bus configuration, the even-numbered slots are assigned SCSI IDs 0 - 4, and
the odd-numbered slots are assigned IDs 8 - 12. (The gap in addresses is necessary for
Correct Disk
Selection Order
1:2
1:3
2:2
2:3
Incorrect Disk
Selection Order
1:2
2:2
1:3
2:3
Primary and mirror
disks on separate
channels.
Primary and mirror
disks on the same
channel.
Pair 1
Pair 2
Pair 2
Pair 1