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

When the onboard SATA ICH9R controller is compared with the LSI MegaRAID SAS 1068 controller, it is evident that

both controllers offer roughly the same performance when measurements are carried out with the same SATA hard disks

and optimum cache settings. The variations in performance are within the range of measuring accuracy.

Relevant differences in throughput were found in

sequential writing and deactivated disk cache. In

this access pattern, the onboard SATA controller is

44% faster than the LSI MegaRAID SAS 1068 con-

troller, however, the absolute throughput values in

both cases are less than 10 MB/s, while the activa-

tion of the disk cache on both controllers leads to an

increase in performance by a factor of 7 or 10 to

70 MB/s.

During random access with enabled disk cache, on

the other hand, the LSI MegaRAID SAS 1068 con-

troller offers about 18% more performance than the

onboard SATA controller.

The onboard SATA controller is implemented di-

rectly on the motherboard of the server in the Intel

ICH9R chipset. The RAID stack is handled by the

server CPU. The increased load on the CPU de-

pends on the access pattern and block size. The

CPU load increases by up to 5 percentage points in

this example, although the CPU load in many small

data blocks is generally higher. Although the on-

board SATA controller features good performance figures, the benefits of the LSI SAS 1068 controller should not go

unmentioned. The advantages of the LSI SAS 1068 controller are not just better performance during random access to

the SATA hard disks, but also greater flexibility and scalability. The LSI SAS 1068 controller supports more RAID levels,

and 3½" and 2½" SAS hard disks with 10 krpm and 15 krpm.

Thanks to the higher rotational speed (15 krpm) of the SAS hard disks, throughputs increases of between about 55% and

193% can be achieved with all access modes in comparison with the SATA hard disks (7.2 krpm). The user must decide

for himself whether his needs are best covered by a less expensive solution with lower performance or a more expen-

sive, higher performance solution.

Conclusion

With the “Modular RAID” concept, the PRIMERGY TX150 S6 offers a plethora of opportunities to meet the various re-

quirements of different application scenarios.

The entry-level controller, represented by the LSI MegaRAID SAS 1068 controller, offers the basic RAID solutions

RAID 0, RAID 1 and RAID 1E and supports these RAID levels with a very good performance.

The “high-end” controller, represented by the LSI MegaRAID SAS 1078 controller, offers all today’s current RAID solu-

tions; for the PRIMERGY TX150 S6, which can be expanded with up to eight internal hard disks, this can be RAID levels

0, 1, 5, 6, 10, 50 and 60. This controller is supplied with a 256 MB or 512 MB controller cache and can as an optional

extra be secured with a BBU. Various options for setting the use of the cache enable controller performance to be flexibly

adapted to suit the RAID levels used.

Use of RAID 5 or RAID 6 enables the existing hard disk capacity to be utilized economically for a good performance.

However, we recommend a RAID 10 for optimal performance and security.

When connecting SATA hard disks in a RAID 0, RAID 1 or RAID 10 array, it is best to use the onboard SATA RAID con-

troller. The throughputs are comparable with those of LSI MegaRAID SAS 1068/1078 controllers and the higher CPU

load on the SATA controller is easily catered for by modern processors. However, with RAID 5 the missing controller

cache of the onboard SATA controller becomes particularly evident during sequential write. If importance is attached to

optimal performance, then an LSI MegaRAID SAS 1078 controller should be chosen for SATA hard disks.

The PRIMERGY TX150 S6 offers a choice between SATA and SAS, and for SAS hard disks between 2½" hard disks

and 3½" hard disks and also different rotational speeds of 10 krpm or 15 krpm. Depending on the performance required,

a decision must be taken as to which hard disk type with which rotational speed is to be used. Hard disks with 15 krpm

offer an up to 39% better performance. As a result of using 2½" hard disks it is possible – depending on the RAID level –

to achieve higher parallelism through the use of more hard disks in the RAID array.

For maximum performance it is advisable, particularly with SATA hard disks or when using a controller without a control-

ler cache, to enable the hard disk cache. Depending on the disk type used and access pattern, the increase in perform-

ance is 13-fold. When the hard disk cache is enabled we recommend the use of a UPS.