Compaq Infortrend Manuale Utente

then distributes data segments to its member drives according to the
specific RAID level it is composed of.

The member logical drives can be composed of the same RAID level
or each of a different RAID level.  A logical volume can be divided
into a maximum of 64 partitions.  During operation, the host sees a
non-partitioned logical volume or a partition of a logical volume as
one single physical drive.

RAID stands for Redundant Array of Independent Disks.  Using a
RAID storage subsystem has the following advantages:

•

 

Provides disk spanning by weaving all connected drives into
one single volume.

•

 

Increases disk access speed by breaking data into several blocks
when reading/writing to several drives in parallel.  With RAID,
storage speed increases as more drives are added as the channel
bus allows.

•

 

Provides fault-tolerance by mirroring or parity operation.

Non-RAID

N

Disk Striping

N

==NRAID

Mirroring Plus Striping (if
N>1)

N/2

>>NRAID

==RAID 5

Striping with Parity on
dedicated disk

N-1

>>NRAID

==RAID 5

Striping with interspersed
parity

N-1

>>NRAID

==RAID 5

Striping with RAID 1
logical drives

/

>>NRAID

>>RAID 5

Striping with RAID 3
logical drives

/

>>NRAID

>>RAID 5

Striping with RAID 5
logical drives

/

>>NRAID

>>RAID 5

NOTE: Drives on different channels can be included in a logical
drive and logical drives of different RAID levels can be used to