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
are recommended.
I/F Name
SAS SSD
NL-SAS (3.5”)
SAS (2.5”)
Rotation speed
－
7.2krpm
10krpm
15krpm
Avg. access time
1.0(m/s)
8.2-9.5(ms)
3.8-4.4(ms)
2.9-3.3(ms)
Power consumption ( idle) (AC)
Approx. 4W
Approx. 9W
Approx. 8W
Max. power consumption (AC)
Approx. 10W
Approx. 14W
Approx. 9W
Max. capacity
1.6TB
6TB
1.8TB
600GB
BER (Bit error rate) at read
-
1/10^15
1/10^16
Random access performance ratio
-
1
1.6
2.4
Backup performance ratio
-
1
1.5
1.5
Restore performance ratio
-
1
1
1.1
Operating time
8 hours/day
365 days
24 hours/day
365 days
Usage
• High random access
performance
• High reliability
• Lower noise
• Large capacity
• Backup/archive
• Low workload (low
random access I/O)
• Mission-critical
• High transaction
Note: The table is reference only.
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NEC Confidential
