User's Manual

272 Protecting Your Virtual Disk with a Hot Spare
• Enclosure affinity settings for a global/dedicated hot spare are not
automatically set when you upgrade to Dell OpenManage version 6.1.
Enclosure affinity settings for a global/dedicated hot spare are not automatically
set when you import a foreign virtual disk.
Considerations for Hot Spares on PERC 4/SC,
4/DC, 4e/DC, 4/Di, 4e/Si, 4e/Di, PERC 5/E, PERC 5/i,
PERC 6/E, PERC 6/I, and CERC 6/I Controllers
On the PERC 4/SC, 4/DC, 4e/DC, 4/Di, 4e/Si, 4e/Di, PERC 5/E, PERC 5/i,
PERC 6/E, PERC 6/I, and CERC 6/I controllers, assigning a hot spare is
equivalent to assigning a physical disk to replace another physical disk if it
fails. If more than one redundant virtual disk resides on the physical disk,
then all redundant portions of the physical disk are rebuilt.
NOTE: When rebuilding a physical disk, you need to delete any non-redundant
virtual disks (such as RAID 0) that reside on the physical disk before rebuilding the
physical disk.
When creating a virtual disk, the physical disks included in the virtual disk
can be different sizes. When assigning a hot spare to a RAID 1 or 5 virtual
disk, the hot spare only needs to be the same size (or larger) as the smallest
physical disk included in the virtual disk.
This is because when using a PERC 4/SC, 4/DC, 4e/DC, 4/Di, 4e/Si, 4e/Di,
PERC 5/E, PERC 5/i, PERC 6/E, PERC 6/I, and CERC 6/I controller, you can
assign physical disks of different sizes to a virtual disk. When you have fully
consumed a smaller physical disk with a virtual disk, however, any portion of
larger physical disks that are not consumed by the virtual disk become
unusable. Therefore, there is no data on the unused portion of a larger disk
that needs to be rebuilt. A redundant virtual disk is also either striped or
mirrored in equal portions across its member physical disks. The amount of
data requiring a rebuild is therefore not larger than the smallest physical disk.
A RAID 10 or 50 virtual disk may include spans that have physical disks of
different sizes. In this case, you should identify the span that has the largest
“small” physical disk. The hot spare should be large enough to rebuild this
physical disk. For example, if one span has three physical disks that are 60
MB, 60 MB and 40 MB and another span has physical disks that are 60 MB,
60 MB, and 50 MB, then the hot spare must be 50 MB or larger.