Samsung 860 EVO 250GB SATA SSD Review

OakGate Platform – Steady State Tests

Sequential Writes to Steady State

This test starts with a purge (Secure Erase), so that the
drive is in a FOB state, and then performs 128K Sequential Writes until twice the
drive’s User Capacity has been written to.

Here is a graph showing the resulting Write Bandwidth over
time –

Samsung 860 EVO 250GB SATA SSD Review

You can see that the performance level falls to a post
TurboWrite speed of just over 300 MB/s after around 25 seconds.  Curiously, the
write speed then steps up at around 300 seconds, and around 760 seconds, to
finally settle into a steady state of roughly 330 MB/s.

Let’s zoom in and have a closer look at the first minute –

Samsung 860 EVO 250GB SATA SSD Review

You can see that the Write Cache (Intelligent TurboWrite)
has enabled the write speed to remain at over 520 MB/s until the total Write
Cache of 12GB (default of 3GB plus intelligent allocation of 9GB, for the 250GB
drive) has been exhausted.

4K Random Writes, FOB to Degraded (Steady State) to Recovered

This test is designed to fully degrade the drive’s
performance and then see how it recovers following a Trim and a period of Rest.

In this test I start with a purge
of the drive to take it to a FOB state.

  1. FOB Performance – 4K Random
    Writes Bandwidth

I then test the FOB 4K Random
Write Performance at Queue Depths of 1 and 32, in an IO Range of 16GB, the
result was as follows –

Samsung 860 EVO 250GB SATA SSD Review

  1. Sequential Writes to two times User Capacity

I then performed 128K Sequential Writes to the drive for
twice the drive’s user capacity (as in the previous Sequential Writes to Steady
State test).

  1. 4K Random Writes for 1 Hour

This was immediately followed by performing 4K Random Writes
to the drive for 1 hour. Here is a graph showing the resulting Bandwidth over
Time –

 

Samsung 860 EVO 250GB SATA SSD Review

You can see that the Random 4K Write performance drops
significantly after around 50 seconds (when the SLC Write Cache is exhausted)
and the performance then settles and heads towards a Steady State of around 27
MB/s.

  1. Fully Degraded, 4K Random Write ‘Steady State’
    Performance

I then immediately test the 4K Random Write Performance, in
an IO Range of 1GB (as we did in the initial FOB test), and the result was as
follows –

Samsung 860 EVO 250GB SATA SSD Review

You can see that performance has dropped significantly
compared to the test performed in the FOB step.  At this stage it is fair to
say that the drive’s performance is fully degraded and in a Steady State.  It’s
as bad as it can get!

  1. Trim and Rest for 5m

I then liberally sent Sequential Trim commands to the drive
for a minute (to ensure that the drive’s entire range of logical blocks (= User
Capacity) was trimmed).

I then let the drive rest for 5 minutes before retesting 4K
Random Write performance again. The result was –

  1. ‘Recovered’ 4K Random Write Performance after Trim and
    5 minutes rest

The outcome was –

Samsung 860 EVO 250GB SATA SSD Review

You can see that the level of performance has improved but
it has not yet approached full recovery.

I the reran the entire series of test steps but with a rest
time of 10 minutes –

  1. ‘Recovered’ 4K Random Write Performance after Trim and
    10 minutes rest

Samsung 860 EVO 250GB SATA SSD Review

The drive has recovered a bit more but is still not
approaching full recovery even with a rest time of 10 minutes.  This is
disappointing when compared to the WD Blue 3D drive that we tested recently,
which had nigh on fully recovered after 5 minutes.  To be fair, I should say
that it is unlikely that any Client SSD will ever be degraded to this extent.

 


Now let’s head to the next page, to look at the
Conclusions from this review…..