Best Practices for the Sun StorEdge 3320 SCSI Array and Sun StorEdge 3310 SCSI Array
3
Logical Drives
A logical drive (LD) is a group of physical drives configured with a RAID level. Each
logical drive can be configured for a different RAID level.
Sun StorEdge 3000 Family SCSI arrays support a maximum of 16 logical drives. A
logical drive can be managed by either the primary or secondary controller. The best
practice for creating logical drives is to add them evenly across the primary and
secondary controllers. The most efficient maximum configuration would have 8
logical drives assigned to each controller. With at least one logical drive assigned to
each controller, both controllers are active. This configuration is known as an active-
active controller configuration and allows maximum use of a dual-controller array's
resources.
Supporting large storage capacities requires using maximum-sized logical drives.
The largest supported logical drive configuration is determined by the size of your
disk drives, cache optimization and the logical drive’s RAID level. Maximizing
existing logical drives before building a new logical drive is recommended. In the
Sun StorEdge 3320 SCSI array, for example, this can result in a supported storage
capacity of 4.68 Tbyte (16 logical drives x 300 Gbyte each = 4.68 Tbyte total capacity).
Each logical drive can be partitioned into up to 32 separate partitions or be used as a
single partition. Partitions are presented to hosts as LUNs.
For information about maximum disk, logical drive, and array capacity, refer to the
Sun StorEdge 3000 Family RAID Firmware User’s Guide
.
Once the logical drives have been created, assigned to a controller, and partitioned,
the partitions must be mapped to host channels as LUNs in order for them to be seen
by a host. It is usually desirable to map each partition to two host channels for
redundant pathing.
A partition can only be mapped to a host channel where its controller has an
assigned ID. For example, if LD 0 is assigned to the primary controller, all partitions
on LD 0 will need to be mapped to a host channel ID on the primary controller
(PID). Any logical drives assigned to the secondary controller will need to have all
partitions mapped to a host channel ID on the secondary controller (SID).
Saving and Restoring Configuration Information
An important feature of these management tools is the ability to save and restore
configuration information in a number of ways. Using the array’s firmware
application, the configuration information (NVRAM) can be saved to disk. This
provides a backup of the controller-dependent configuration information such as
