Technical data

White Paper ⏐Performance Report PRIMERGY TX150 S6 Version: 5.1, November 2008

LSI MegaRAID SAS 1068

Below is a comparison of the performance of various hard disk types with the LSI MegaRAID SAS 1068 controller. The

controller does not have a controller cache. Therefore, measurements were only performed with and without a disk

cache.

In the test setup two hard disks were connected to the controller and configured as a RAID 1. In the measurements all

the hard disk types currently available to the PRIMERGY TX150 S6 were analyzed. The throughputs of the individual

hard disks types in RAID 1 are compared below with different access patterns.

The diagram shows that as the rotational speed increases, the throughput for sequential reads and writes with a 64 KB

block size rises.

If for sequential read with enabled disk cache a hard disk with a rotational speed of 15 krpm is used instead of one with a

speed of 10 krpm, the result for the 2½" hard disk is an increase in throughput of about 27% and about 43% for the 3½"

hard disk. If you compare the throughputs of the 2½" and 3½" hard disks both with a rotational speed of 10 krpm, you

can see that the throughput for the 3½" hard disk is about 9% higher than for the 2½" hard disk. At a rotational speed of

15 krpm the difference in throughput between the 2½" and 3½" hard disk is even greater and amounts to 23%.

If you compare the 3½" SAS hard disk with the 3½" SATA hard disk, you can then see that the throughput of the SAS

hard disk with 10 krpm is about 12% higher than the SATA hard disk with 7.2 krpm for sequential read and with an en-

abled disk cache. If you compare the 3½" SAS hard disk with 15 krpm with the SATA hard disk, you see that the

throughput of the 3½" SAS hard disk with 15 krpm is even 60% higher than with the SATA hard disk.

If for sequential write with enabled disk cache a hard disk with a rotational speed of 15 krpm is used instead of one with a

speed of 10 krpm, the result for the 2½" hard disk is an increase in throughput of about 26% and about 39% for the 3½"

hard disk. If you compare the throughputs of the 2½" and 3½" hard disks both with a rotational speed of 10 krpm, you

can see that the throughput for the 3½" hard disk is about 4% higher than for the 2½" hard disk. At a rotational speed of

15 krpm the difference in throughput between the 2½" and 3½" hard disk is even greater and amounts to 15%.

If you compare the 3½" SAS hard disk with the 3½" SATA hard disk, you can then see that the throughput of the SAS

hard disk with 10 krpm is about 18% higher than the SATA hard disk with 7.2 krpm for sequential write and with an en-

abled disk cache. If you compare the 3½" SAS hard disk with 15 krpm with the same SATA hard disk, you see that the

throughput of the 3½" SAS hard disk with 15 krpm is even 63% higher than with the SATA hard disk.

A special increase in throughput for sequential write, up to 10.4-fold, can be achieved with the SATA hard disk by ena-

bling the disk cache. The increase in throughput gained with SAS hard disks through enabling the disk cache is not so

pronounced as with the SATA hard disks, but it is still significant. For the 2½" hard disks with 10 krpm throughput in-

creases by 44% and by about 62% for the 2½" hard disks with 15 krpm. For the 3½" hard disks with 10 krpm throughput

increases by 34% and by about 66% for the 3½" hard disks with 15 krpm.