User manual

FIBRE-to-SAS/SATA RAID SUBSYSTEM
68
User Manual
6.1.1.1 Number of Disks Available
The number of physical disks that are available will influence your decision about
which RAID level you can choose and whether or not you can have a spare drive(s).
The following table shows the minimum number of disks that are required to
implement each RAID level.
If you wish to have a Spare Drive, you will need to have at least the minimum
number of disks, plus a disk for every Spare Drive you require.
NOTE: To create a RAID 10, select multiples of two disks and select
RAID 1. The RAID Level will still show as “RAID 1” but the RAID
capacity is correct.
6.1.1.2 Spare Drive Strategy
A Spare Drive is a disk drive that is set aside when creating your RAID system so
that it can be used to rebuild a RAID in the event of a disk drive in that RAID failing.
This reduces the risk to your data as the RAID can be rebuilt immediately without
installing a new disk to replace a failed disk in the RAID.
When creating your RAID Set you must consider which Sparing Strategy you want
to implement. There are 3 possible Sparing Strategies available in ProRAID
Manager: None, Local, and Global.
A Local Spare Drive is a spare disk that is only available to the RAID Set in which
it was created. If a disk fails in a RAID Set in the system, a Local Spare from
another RAID Set cannot be used to rebuild the degraded RAID Set.
A Global Spare Drive is a spare disk that is available to all RAID Sets in the
system. If a disk fails in any RAID Set in the system, the Global Spare disk can be
used to rebuild the degraded RAID Set.
NOTE: A Spare Disk must have capacity equal to or greater than
the capacity of the disks in the RAID Set(s) to which it is assigned.
RAID Level
Minimum Number of
Disks
0 1
1 2
10 4
5 3
6 4