Performance Consistency

Our performance consistency test explores the extent to which a drive can reliably sustain performance during a long-duration random write test. Specifications for consumer drives typically list peak performance numbers only attainable in ideal conditions. The performance in a worst-case scenario can be drastically different as over the course of a long test, as drives can run out of spare area and have to start performing garbage collection as well as sometimes even reach power or thermal limits.

In addition to an overall decline in performance, a long test can show patterns in how performance varies on shorter timescales. Some drives will exhibit very little variance in performance from second to second, while others will show massive drops in performance during each garbage collection cycle but otherwise maintain good performance, and others show constantly wide variance. If a drive periodically slows to hard drive levels of performance, it may feel slow to use even if its overall average performance is very high.

To maximally stress the drive's controller and force it to perform garbage collection and wear leveling, this test conducts 4kB random writes with a queue depth of 32. The drive is filled before the start of the test, and the test duration is one hour. Any spare area will be exhausted early in the test and by the end of the hour even the largest drives with the most overprovisioning will have reached a steady state. We use the last 400 seconds of the test to score the drive both on steady-state average writes per second and on its performance divided by the standard deviation.

Steady-State 4KB Random Write Performance

The X400's steady-state write performance is unimpressive but typical for planar TLC drives.

Steady-State 4KB Random Write Consistency

The consistency score of the X400 is good but not great, and it is again close to the OCZ Trion 150.

IOPS over time
Default
25% Over-Provisioning

The X400 does not display an initial burst of extreme performance and instead wobbles around 20k IOPS before dropping down to steady state. The X400 does not exhibit severe stalling at any stage of the test, whereas the previously reviewed Trion 150 handles the transition to steady state poorly.

Steady-State IOPS over time
Default
25% Over-Provisioning

In steady-state the X400's performance is not tightly regulated but doesn't have any outliers of significantly below-average performance. Extra overprovisioning does little to improve the worst-case performance but greatly increases the average and best-case write performance.

Introduction AnandTech Storage Bench - The Destroyer
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  • Chaitanya - Friday, May 6, 2016 - link

    1TB capacity in M.2 Form factor is tempting. Reply
  • nathanddrews - Friday, May 6, 2016 - link

    I like the $/GB, but there aren't enough GBs. Reply
  • Namisecond - Sunday, May 8, 2016 - link

    Maybe you need to stop treating SSDs as bulk storage? Reply
  • dsumanik - Sunday, May 8, 2016 - link

    Maybe you should go back to floppies.

    It's 2016 and there is no reason for magnetic drives to be alive. Yes yes, I know about cost per gig and all the stats you feel like googling and quoting to me to prove how smart you are, but the real truth is this: it's way more profitable to sell us 50 year old technology cuz dums dums will keep on buying.

    Bring on xpoint, it'll help push traditional flash down into the bargain bin... And for u sir, Ii will gladly mail you my original dos 6.22 install disks if you simply shut the f**k up.
    Reply
  • santeana - Monday, May 9, 2016 - link

    LMAO! I wish there was a like button!

    +1
    Reply
  • blakeatwork - Monday, May 9, 2016 - link

    It's a process of how quickly do you need to access certain types of data. OS, programs and games all benefit from being on an SSD (assuming supporting architecture does not have any obvious bottlenecks). I'm not sure browsing photos from a recent vacation really provides the necessary strain on your I/O that requires an SSD :D
    Magnetic drives will stick around for quite a while, especially for Home/SMB NAS devices where the amount of storage is greater then the perceived need for super fast access, which is throttled by GbE network (or WiFi) anyways
    Reply
  • bug77 - Tuesday, May 10, 2016 - link

    Modern operating system do lots of stuff in the background, an AV may scan your drives from time to time. This is stuff that kills IO on a HDD and that barely registers on a SSD. So there are reason for moving away from HDDs... But yes, the HDD will stick around for a while, simply because of pricing. Reply
  • jordanclock - Saturday, July 2, 2016 - link

    Good thing we just dump all old technology as soon as we find a replacement! Reply
  • edward1987 - Thursday, September 22, 2016 - link

    1TB is quite out of my pocket £218 (http://www.span.com/product/SanDisk-X400-SSD-SD8SN... but 512GB I would not mind. If you have Qnap tvs-1282 server or similar - they have m.2 for caching or tiered storage. I can use for it in there. Reply
  • HollyDOL - Friday, May 6, 2016 - link

    There is a mismatch in Specification table:
    1TiB (1024GB) should be 1TB(1000GB)
    According to specs at https://www.sandisk.com/content/dam/sandisk-main/e...

    putting 10^3n and 2^10n prefixes together is just incorrect anyway without correct recalculation...
    Reply

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