Performance Consistency

Performance consistency tells us a lot about the architecture of these SSDs and how they handle internal fragmentation. 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 (Logical Block Addresses) 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 dropdown selections 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.

Transcend SSD370 256GB
25% Over-Provisioning

Despite the custom Transcend firmware, performance consistency is an exact match with ADATA's SP610. I'm suspecting that the reason for low steady-state performance might be the hardware because the SM2246EN is a single-core design. Most controller designs today are multicore because today's NAND requires a lot of management and with multiple cores the NAND management can be dedicated to one or more cores, which leaves the rest of the cores available for host IO processing. In Silicon Motion's case, the one core has to take care of everything from host IOs to NAND management, which translates to lower overall performance as the controller can't keep up with everything that needs to be done.

Transcend SSD370 256GB
25% Over-Provisioning


Transcend SSD370 256GB
25% Over-Provisioning

TRIM Validation

To test TRIM, I filled a 128GB SSD370 with sequential 128KB data and proceeded with a 30-minute random 4KB write (QD32) workload to put the drive into steady-state. After that I TRIM'ed the drive by issuing a quick format in Windows and ran HD Tach to produce the graph below.

And TRIM works as expected.

Introduction, The Drive & The Test AnandTech Storage Bench 2013


View All Comments

  • danko358 - Wednesday, September 23, 2015 - link

    Compared to other SSDs power consumption of SSD370 is high, as seen in review. What about comparing it to regular HDDs? As I understand, it's the same. I'm asking because I'm considering replacing regular HDD in my laptop with SSD370 256. So my battery life will remain the same? It won't be shortened? Reply
  • amirzz - Thursday, December 24, 2015 - link

    this is to inform all concerned, I don't get in what technology transcend SSD370 is made up of...
    I've recently bought one of this & now after keeping a backup of my crucial data here...
    one folder containing my tutorials is not respondins as needed... I don't seem to find any solutions anywhere in the net....
    so plz experts in ssd help me here...
    my email: neobondhu[at] gmail[dot] com
  • Firedrops - Monday, February 29, 2016 - link

    You really should provide screenshots of actual capacities in these reviews. There can be easily ~10GB difference in capacity between brands/models even when labelled similarly, at ~240-256GB capacities. Reply
  • lenberg - Thursday, September 15, 2016 - link

    Does anyone know how to align partitions in this ssd properly?
    What are the NAND Erase Block Size and NAND Page Size?
    Thanks in advance.

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