OCZ Agility 4 (256GB) Review

Performance vs. Transfer Size

All of our IOmeter sequential tests happen at a queue depth of 1, which is indicative of a light desktop workload. It isn't too far fetched to see much higher queue depths on the desktop. The performance of these SSDs also greatly varies based on the size of the transfer. For this next test we turn to ATTO and run a sequential write over a 2GB span of LBAs at a queue depth of 4 and varying the size of the transfers.

One of our main complaints about the firmware 1.4/1.5 for Vertex 4 was poor sequential read performance at small transfer sizes. Unfortunately, Agility 4 is even worse. With larger transfers, performance is okay, although not top notch. Once we go under 64KB IO size, the performance falls off considerably. For example at transfer size of 16KB, Agility 4 manages only 95.7MB/s, whereas Samsung 830 is reading at nearly 500MB/s. The good news is most client SSD performance isn't bound by small sequential transfers, but it's still a limitation of the drive.

Fortunately there is no such problem with sequential write performance. Vertex 4 is still faster but only at bigger transfer sizes and even then the difference is not too bad (~50MB/s).