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Performance in Intel IOMeter

Database Pattern

In the Database pattern the disk array is processing a stream of requests to read and write 8KB random-address data blocks. The ratio of read to write requests is changing from 0% to 100% throughout the test while the request queue size varies from 1 to 256.

We’ll be discussing diagrams but you can view tabled data using the following links:

We’ll discuss the results for queue depths of 1, 16 and 256.

The HighPoint controller looks better at minimum loads. It copes better with a single disk and delivers higher performance than its opponent with RAID1 and RAID10 arrays. We can see that the Promise controller has problems with the RAID1. Its RAID1 array turns to be slower than the single drive at mixed loads (at 25 to 75 writes), indicating certain flaws in the controller’s algorithms.

The controllers are both good with RAID0 at minimum load. They are different, though. The HighPoint is better at writes-only load whereas the Promise is better when there is a small share of reads to be processed.

Both controllers have problems with RAID5. The three-disk array proves to be faster than the four-disk RAID5 with the HighPoint controller. The difference is small, yet it makes us wonder what performance RAID5 arrays with even more disks would deliver. The two arrays are roughly similar with the Promise controller, and both slow down considerably and inexplicably at high percentages of writes.

Take note of the performance hit suffered by the degraded arrays. Four minus one is not the same as three when we are talking about RAID arrays.

There are no smooth graphs in the RAID6 diagram, yet the arrays can be compared in general. The Promise copes better when in ordinary mode, losing to the opponent at pure writing only. Moreover, its degraded minus-one array proves to be faster at reading than the ordinary RAID6 on the HighPoint controller. However, the Promise controller has problems again when there is a higher percentage of writes. Perhaps its processor cannot cope with the XOR load due to some peculiarities in the firmware.

When two disks fail, the HighPoint proves to be competitive to the Promise and even superior to it at writing.

When we increase the queue depth to 16 requests, the HighPoint wins with a huge lead with the mirror arrays. The Promise is so much slower at high percentages of reads that it seems to have problems reordering requests for mirror arrays. This is the only explanation we can think of concerning the performance slump in the left part of the diagram.

 
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