ADATA Premier SP610 SSD (256GB & 512GB) Review: Say Hello to an SMI Controller

Performance Consistency

Performance consistency tells us a lot about the architecture of these SSDs and how they handle internal defragmentation. The reason we do not have consistent IO latency with SSDs is because inevitably all controllers have to do some amount of defragmentation or garbage collection in order to continue operating at high speeds. When and how an SSD decides to run its defrag or cleanup routines directly impacts the user experience as inconsistent performance results in application slowdowns.

To test IO consistency, we fill a secure erased SSD with sequential data to ensure that all user accessible LBAs have data associated with them. Next we kick off a 4KB random write workload across all LBAs at a queue depth of 32 using incompressible data. The test is run for just over half an hour and we record instantaneous IOPS every second.

We are also testing drives with added over-provisioning by limiting the LBA range. This gives us a look into the drive’s behavior with varying levels of empty space, which is frankly a more realistic approach for client workloads.

Each of the three graphs has its own purpose. The first one is of the whole duration of the test in log scale. The second and third one zoom into the beginning of steady-state operation (t=1400s) but on different scales: the second one uses log scale for easy comparison whereas the third one uses linear scale for better visualization of differences between drives. Click the buttons below each graph to switch the source data.

For more detailed description of the test and why performance consistency matters, read our original Intel SSD DC S3700 article.

	ADATA SP610	ADATA SP920	JMicron JMF667H (Toshiba NAND)	Samsung SSD 840 EVO mSATA	Crucial MX100
Default
25% OP

Ouch, this doesn't look too promising. The SMI controller seems to be very aggressive when it comes to steady-state performance, meaning that as soon as there is an empty block it prioritizes host writes over internal garbage collection. The result is fairly inconsistent performance because for a second the drive is pushing over 50K IOPS but then it must do garbage collection to free up blocks, which results in the IOPS dropping to ~2,000. Even with added over-provisioning, the behavior continues, although now more IOs happen at a higher speed because the drive has to do less internal garbage collection to free up blocks.

This may have something to do with the fact that the SM2246EN controller only has a single core. Most controllers today are at least dual-core, which means that at least in one simple scenario one core can be dedicated to host operations while the other handles internal routines. Of course the utilization of cores is likely much more complex and manufactures are not usually willing to share this information, but it would explain why the SP610 has such a large variance in performance.

As we are dealing with a budget mainstream drive, I am not going to be that harsh with the IO consistency. Most users are unlikely to put the drive under a heavy 4KB random write load anyway, so for light and moderate usage the drive should do just fine because ~2,000 IOPS at the lowest is not even that bad -- and it's still a large step ahead of any HDD.

	ADATA SP610	ADATA SP920	JMicron JMF667H (Toshiba NAND)	Samsung SSD 840 EVO mSATA	Crucial MX100
Default
25% OP

Just to put things in perspective, however, even the over-provisioned "384GB" SP610 ends up offering worse consistency than the 128GB JMicron JMF667H SSD. Pricing will need to be very compelling if this drive is going to stand up against drives like the Crucial MX100.

	ADATA SP610	ADATA SP920	JMicron JMF667H (Toshiba NAND)	Samsung SSD 840 EVO mSATA	Crucial MX100
Default
25% OP

TRIM Validation

To test TRIM, I first filled all user-accessible LBAs with sequential data and continued with torturing the drive with 4KB random writes (100% LBA, QD=32) for 30 minutes. After the torture I TRIM'ed the drive (quick format in Windows 7/8) and ran HD Tach to make sure TRIM is functional.

And it is.