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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.

Under the server-like load of read requests, the RAID10 are always ahead of the RAID0 by reading from the “better” disk in a mirror.

The checksum-based arrays produce neat graphs, too. There are no surprises here.

The performance ratings are perfectly understandable. The mirror arrays are ahead. The performance of the others depends only on the number of disks in them. As the load is close to random reading, the RAID5 and RAID6 arrays are about as fast as the RAID0. The high-performance processor helps minimize the negative effect of data recovery from checksums for the degraded arrays. The resulting performance hit is comparable to just decreasing the array by one disk.

When there is a small share of writes in the load, the RAID10 are only victorious at short queue depths. The RAID0 arrays win at long queue depths.

The write requests make the RAID6 fall behind the RAID5. The performance of the RAID6 degraded by two disks slumps greatly, especially at short queue depths.

Since our performance rating formula gives higher weights to the results at short queue depths, the RAID10 are just a little worse than the same-size RAID0.

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