Technical data

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

Measurement scenario

In order to obtain comparable measurement results it is important to perform all the measurements in identical, repro-

ducible environments. This is why StorageBench is based, in addition to the load profile described above, on the follow-

ing regulations:

• Since real-life customer configurations work only in exceptional situations with raw devices, performance

measurements of internal disks are always conducted on disks containing file systems. NTFS is used for

Windows and ext3 for Linux, even if higher performance could possibly be achieved with other file systems or

raw devices.

• Hard disks are among the most error-prone components of a computer system. This is why RAID controllers are

used in server systems in order to prevent data loss through hard disk failure. Here several hard disks are put

together to form a “Redundant Array of Independent Disks”, known as RAID in short – with the data being

spread over several hard disks in such a way that all the data is retained even if one hard disk fails – except

with RAID 0. The most usual methods of organizing hard disks in arrays are the RAID levels RAID 0, RAID 1,

RAID 5, RAID 6, RAID 10, RAID 50 and RAID 60. Information about the basics of various RAID arrays is to be

found in the paper Performance Report - Modular RAID for PRIMERGY.

Depending on the number of disks and the installed controller, the possible RAID configurations are used for the

StorageBench analyses of the PRIMERGY servers. For systems with two hard disks we use RAID 1 and

RAID 0, for three and more hard disks we also use RAID 1E and RAID 5 and, where applicable, further RAID

levels – provided that the controller supports these RAID levels.

• Regardless of the size of the hard disk, a measurement file with the size of 8 GB is always used for the

measurement.

• In the evaluation of the efficiency of I/O subsystems, processor performance and memory configuration do not

play a significant role in today’s systems - a possible bottleneck usually affects the hard disks and the RAID

controller, and not CPU and memory. Therefore, various configuration alternatives with CPU and memory need

not be analyzed under StorageBench.

Measurement results

For each load profile StorageBench provides various key indicators: e.g. “data throughput” in megabytes per second, in

short MB/s, “transaction rate” in I/O operations per second, in short IO/s, and “latency time” or also “mean access time” in

ms. For sequential load profiles data throughput is the normal indicator, whereas for random load profiles with their small

block sizes the transaction rate is normally used. Throughput and transaction rate are directly proportional to each other

and can be calculated according to the formula

Data throughput [MB/s] = Transaction rate [Disk-I/O s

-1

] × Block size [MB]

Transaction rate [Disk-I/O s

-1

] = Data throughput [MB/s] / Block size [MB]