3PAR InForm® OS 2.2.4 Concepts Guide (320-200085 Rev B, March 2009)

7.4
Logical Disks and Physical Disks
3PAR InForm OS Concepts Guide InForm OS Version 2.2.4
7.4.2 For Common Provisioning Groups
When creating a common provisioning group, the system may also round up to determine the
initial allocation as well as the growth increment that determines the size of subsequent
allocations that occur as the CPG grows over time. For example, when creating a RAID 5 CPG
with the default set size of 3 and a growth increment of 8192 MB, the system will
automatically create a CPG with an initial user size of 8448 MB and a growth increment of 8448
MB. The system must round up the user space because the CPG requires 11 underlying RAID 5
logical disks, each with a size of 768 MG (3 x 256 MB). Together, these 11 logical disks total
8448 MB (11 x 768 MB).
7.5 Logical Disks and Physical Disks
If some physical disks in the system are unavailable on power up (i.e., they are in the missing
state), the system manager will not immediately start up the logical disks that have chunklets
on these disks. The result of this is that some logical disks remain in the stopped state in the
output for the InForm CLI
showld command on cluster reboot, and some physical disks are in
the missing state in the
showpd output.
If the logical disk is data-complete, but a few of the physical disks are missing, the logical disks
will be started after waiting five minutes. Also, if more than four physical disks are missing, the
logical disks will not be started automatically. You can start a data-complete logical disk using
the InForm CLI
startld command (refer to the InForm OS Command Line Interface Reference
for details), and the system manager will begin reconstructing the missing mirrored data.
The system automatically relocates the chunklets from the missing physical disks to free space
or spare space. As each physical disk is completely vacated, the logical disk is automatically
started. The operator can also start logical disks manually, however the system should start the
logical disks once the physical disk’s chunklets are vacated from that disk.