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Web-Server, File-Server, Workstation Patterns

The controllers are tested under loads typical of servers and workstations.

The names of the patterns are self-explanatory. The request queue is limited to 32 requests in the Workstation pattern. Of course, Web-Server and File-Server are nothing but general names. The former pattern emulates the load of any server that is working with read requests only whereas the latter pattern emulates a server that has to perform a certain percent of writes.

The 8-disk RAID10 is unrivalled at pure reading as it can effectively read from both disks of a mirror couple. But you can note that the failure of one disk worsens its performance greatly.

The RAID5 and RAID6 arrays go neck and neck. The failure of one disk lowers their performance by 50%. The loss of a second desk cuts the performance of the RAID6 by 50% more.

The performance ratings indicate that the number of disks per array is more important under such load than the array type. However, RAID10 is preferable, the other parameters being equal, if you are looking for maximum speed.

The RAID10 is not a leader anymore when there are write requests to be performed. It is still good at short queue depths but loses to the RAID0 at long queue depths.

While the 4-disk RAID5 and RAID6 are similar in terms of performance, the 8-disk RAID5 is ahead of the same-size RAID6. The degraded arrays slow down greatly, yet even the RAID6 with two failed disks performs better than on competitor controllers.

Lower queue depths have higher weights in our performance rating formula, but this doesn’t help the RAID10 get closer to the RAID0. The checksum based arrays find this test difficult: processing those checksums has a negative effect on their performance.

The standings are the same here as in the File-Server test. The positions of the two degraded arrays have changed somewhat. The RAID10 is now closer to the healthy RAID10, and the RAID6 without two disks has sunk to the level of the single HDD.

The RAID6 arrays have moved down to lower places. We don’t think they should be used in highly loaded workstations, though.

When the test zone is limited to 32GB, each array increases its gap from the single HDD.

 
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