4. Disk Drive (1)
(1) Disk Drive Size and Type
M-Series products support the following types of drives: SSD, SAS, and NL-SAS. Performance,
reliability, and price of disk drives vary depending on the type and size. Select the proper disk drive
according to the intended application.
(1-1) Disk Drive Size
There are two relevant form factors of disk drives: 2.5" and 3.5".
■ 2.5" HDD
The maximum rotation speed is 15krpm for a high performance HDD.
2U chassis can support up to 24 HDDs.
■ 3.5" HDD
The larger 7.2krpm NL-SAS drive topology offers an excellent cost per capacity ratio.
(1-2) Disk Drive Type
n SSD (Solid State Drive)
Unlike a conventional HDD, SSD does not have mechanical parts such as motors, heads and media.
Reliability and random access performance is superior to conventional HDD. SSD is a "green" product
because it reduces power consumption.
- SAS SSD: High performance, High reliability
n SAS HDD (Serial Attached SCSI Hard Disk Drive)
SAS HDD is excellent in reliability and performance. It is good for mission-critical systems that require
high-performance and non-stop operation.
n NL-SAS HDD (NL-Serial Attached SCSI Hard Disk Drive)
NL-SAS is a high capacity and low cost HDD. It is good for backup and archive and can be used for
workloads which do not require high volumes of random access I/O. Because NL-SAS HDD has large
capacity and low performance, it takes longer time to recover compared to SAS HDD.
From the perspective of reliability, double redundancy RAID types such as RAID-6 or RAID-TM
Avg. access time
Power consumption ( idle) (AC)
Max. power consumption (AC)
BER (Bit error rate) at read
Random access performance ratio
Backup performance ratio
Restore performance ratio
Note: The table is reference only.
• High random access
• Large capacity
• High reliability
• Low workload (low
• Lower noise
random access I/O)
• High transaction