Matrix RAID

In the next series of graphs we have the RAID0 partition created first . The WD1200 is made up of 2 60GB platters. We chose to allocate 120GB for the RAID0 partition (60GB on each drive) and 60GB for the RAID1 mirror (again, 60GB on each drive). The thinking is that in the most simple disk partitioning scheme, each partition would get its own entire platter. Of course, this is not the most efficient method for partitioning for performance - the highest disk performance comes from the outer edge of the hard disk and as the heads move inward, the circumferance gets smaller and because less data is read or written every revolution, this means that performance drops as a result. This is not how it works as we see from the results of the previous page. Instead the disk platters are partitioned like so -

The black area in this instance is the RAID0 partition on each of the platters while the white area is the RAID1 partition.

Single Drive vs RAID1

Remember our chart from the previous page when we compared the single drive against the pair of disks that were dedicated to RAID1 - the performance was nearly spot on between the single drive when compared to the RAID1 disks.

The RAID1 partition was created AFTER the RAID0 partition and the results can be seen above. The performance is not the same as what we saw on the previous page. Look what happens though after we shift the graph - it matches up with the second half of the single drive test results almost exactly.

Single Drive vs RAID0

We see a lot of variance in the performance of the RAID0 partition - the write speed has a sinusoidal pattern - we are suspecting that the disk position for each platter is staggered but we still have trouble explanating the variation in performance as we move across the disk. Reading is a little bit more stable as looks as it becomes more so as we move across the drive. Note that we are seeing almost no performance drop as we are moving across the hard disk on the RAID0 write process.

RAID0 vs RAID1 in Matrix RAID - RAID0 partition created first