Multithreaded Read & Write Patterns

The multithreaded tests simulate a situation when there are one to four clients accessing the virtual disk at the same time – the clients’ address zones do not overlap. We will discuss diagrams for a request queue of 1 as the most illustrative ones – the speed doesn’t depend much on the number of applications at a request queue of 2 and longer.

You can click the following links for full results:

• IOMeter Multithreaded Read results for RAID0
• IOMeter Multithreaded Read results for RAID10
• IOMeter Multithreaded Read results for RAID5
• IOMeter Multithreaded Write results for RAID0
• IOMeter Multithreaded Write results for RAID10
• IOMeter Multithreaded Write results for RAID5

It is yet another test won by the Western Digital RE3. It is the best at multithreaded reading in RAID0. Its performance hit with multiple data threads is small.

Seagate’s new series drives behave in an odd way. They did not like to switch from one to two threads but improved their performance when there were even more threads to process.

The Western Digital RE2 and the Hitachi are the best of the older drives here.

The RE3 is just excellent when reading in a RAID10 array. It not only reads from two disks at once but also improves its performance when processing an even number of threads. The controller ideally distributes the read threads among the different drives in the mirrors.

The other HDDs behave like in the RAID0 arrays: the new models from Seagate again improve their speed when switching from two to three threads and take second and third places. The RE2 and the Hitachi are still the best among the three-platter products.

There are no changes when we switch to RAID5.

The large total amount of cache memory allows to perform multithreaded reading in RAID0 with a minimum loss irrespective of the number of threads. There are a couple of interesting things, though.

First, the Hitachi and the Seagate 7200.11 are the only drives to switch to multiple threads without any loss of speed. Interestingly, the enterprise counterpart of the latter model is among those two HDD that suffer the heaviest performance hit (the Western Digital RE3 is the other one; it has weak spots after all).

It is different with the RAID10 arrays: the RE3 regains its leadership whereas the two new products from Seagate are no good at multithreading. Both are more or less good with two threads but slow down with more threads.

There are no obvious losers with RAID5, but we have two leaders. The RE3 is a traditional leader already while the Samsung is a new face at the top.