Datasheet

NEC Confidential
15
2. M100 Component Selection (10)
(4-3) Disk Drive Usage
Both base unit and SAS disk enclosures can include a mix of SAS/Nearline SAS/SAS SSD disk drives
and disk drives with different capacities and rotation speeds.
A pool must contain disk drives with the same interface. The capacity or rotation speed does not matter.
However, it is strongly recommended to have the same capacity and the same rotation speed in the
same pool. When having different capacities of disk drive in a pool, the pool will be created based on
the disk drive with the smallest capacity. In this case, the differences between larger disk drives and
the smallest disk drives are not used. Note that SAS and Nearline SAS are different interfaces.
<Example>
A pool configured by SAS disk drives (15krpm/300GB) and SAS disk drives (15krpm/600GB)
 The SAS disk drive (15krpm/600GB) is treated as a SAS disk drive (15krpm/300GB).
When using different speeds of disk drives in a pool, the pool will be created based on the slowest disk
speed. In this case, performance will not be as good as expected because drives with faster speed are
treated the same as drives with the slowest speed.
<Example>
A pool configured by 3.5” SAS disk drives (15krpm/300GB) and 2.5” SAS disk
drive(10krpm/300GB)
 The SAS disk drive (15krpm/300GB) is treated as a SAS disk drive (10krpm/300GB).
* RAID-0: Data is not protected.
RAID Type Configuration Number of physical disk drives Redundancy RAID Capacity
RAID-0 * None Physical disk capacity x 1
RAID-1/10 (1+1) x n 2 or more disk drives 1 Physical disk capacity x 1/2
RAID-5/50 (2+P) x n 3 or more disk drives 1 Physical disk capacity x 2/3
(4+P) x n 5 or more disk drives 1 Physical disk capacity x 4/5
(8+P) x n 9 or more disk drives 1 Physical disk capacity x 8/9
RAID-6/60 (4+PQ) x n 6 or more disk drives 2 Physical disk capacity x 2/3
(8+PQ) x n 10 or more disk drives 2 Physical disk capacity x 4/5
RAID-TM (1+1+1) x n 3 or more disk drives 2 Physical disk capacity x 1/3
(4-4) Supported RAID
NEC Storage M-Series supports the following RAID types. (Note: Only RAID-1, 10, 5(4+P), 50(4+P)
are supported with SSD)
(4-5) Dynamic Pool
NEC Storage Ｍ-Series supports only dynamic pools. LUN capacity can be modified dynamically.
Capacity is constant regardless of the number of disk drives. It is slightly less than the table on the
previous page. Striping is automatic when an applicable number of disk drives are used with RAID
types that support striping.
Example: RAID-1 with 4 disk drives is automatically configured as RAID-10.
Refer to “5. Functions <Pool>” for more details about Dynamic Pool.