Specifications

4–16 Planning Storagesets
■ Place mirrorsets and RAIDsets on different ports to minimize risk in the event of
a single port bus failure.
■ Mirrorset units are set to WRITEBACK_CACHE by default which increases a
unit’s performance.
■ A storageset should only contain disk drives of the same capacity. The controller
limits the capacity of each member to the capacity of the smallest member in the
storageset. Thus, if you combine 9 GB disk drives with 4 GB disk drives in the
same storageset, the 4 GB disk drive will be the base member size, and you waste
5 GB of capacity on each 9 GB member.
■ Evenly distribute the members across the device ports to balance load and
provide multiple paths as shown in Figure 4–4 on page 4–12.
■ Mirrorsets are well-suited for the following:
❏ Any data for which reliability requirements are extremely high
❏ Data to which high-performance access is required
❏ Applications for which cost is a secondary issue
■ Mirrorsets are not well-suited for the following applications:
❏ Write-intensive applications (JBODs are better for this type of application,
but mirrorsets are preferred over Raid5 RAIDsets.)
❏ Applications for which cost is a primary issue
Using RAIDsets to Increase Performance and
Availability
RAIDsets are enhanced stripesets—they use striping to increase I/O performance and
distributed-parity data to ensure data availability. Figure 4–7 illustrates the concept of
RAIDsets and parity data.