Tandberg Data
BakStor Installation and Administration Manual
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as compromised as RAID-1.
Example
In the BakStor there are 4 x 250GB capacity disk drives. By creating a RAID-5 one logical drive
with a size of 750GB will be available instead of four single 250GB drives.
(4 x 250GB – 1 x 250GB for parity =750GB usable)
RAID-5+hot spare (Multiple Block Striping with Interspersed Parity and dedicated spare drive)
RAID-5 + hot spare has the same instances as RAID5 except it has a dedicated hot spare drive
that is not part of the Logical drive but stands by in case of a drive failure.
In case of a drive failure the BakStor will immediately start the process of incorporating the
spare drive into the RAID-5.
Typically RAID-5/RAID-5 + hot spare are the most popular cost effective RAID level used in
today’s industry environments.
2 TB limit
Note that the current version of the BakStor is not able to create a RAID larger than 2TB.
Depending on the capacity of the disks in the BakStor this may mean that not all the disks can
be configured into a single RAID.
For instance, with a disks size of 400GB, only 6 disks can be configured in single RAID 5 set.
In order to utilize all disks in a BakStor 2000, several RAID sets are needed.
4.1.4 Shared hot spare drive
On a BakStor 2000 there are enough disk drives (12) to create multiple RAID sets. In order to
cut down on the number of disk drives used as hot spare drives it is possible to configure a disk
drive as a “shared spare drive”. This way one single disk drive can act as a hot spare for
multiple RAID sets. In the case of a failure in one RAID set the shared spare drive will be used
in this RAID set. If there is a failure in the second RAID set as well there will be no spare drive
available for the second RAID set and it will run in degraded mode until the faulty disk in the
second RAID set has been replaced.
