Oakgate Platform – Sustained Write and Recovery Tests
Sustained Sequential Writes
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
You can see that the Toshiba Q300 PRO 1024GB holds a steady
speed of 510 MB/s until 1062 seconds have passed. This is clear evidence of the
Q300 PRO’s Adaptive SLC Write Cache Technology being in play – as the drive is
empty at the start of the test, the drive is able to write to around half of
its total capacity in an accelerated 1 bit SLC mode, before it has to flush its
SLC Write Cache, and then continue in 2 bit mode. We can infer from this result
that the Q300 PRO will sustain a sequential write speed of 510 MB/s whilst the
file size being written does not exceed half of the space available at the
start of the write task. So, for example, if the amount of space used is 512GB
on a 1024GB model then a sustained sequential write task can write
approximately 256GB of data before a drop in speed will be detected.
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.
- FOB Performance – 4K Random
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 –
- 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
- 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
You can see that the Random 4K Write performance eventually
settles into a steady state which fluctuates around an average of approximately
- Fully Degraded, 4K Random Write ‘Steady State’
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
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!
- 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 –
- ‘Recovered’ 4K Random Write Performance after Trim and
5 minutes rest
The outcome was –
You can see that performance has fully recovered to an FOB
state. Perfect – an outstanding result.
Now let’s head to the next page, to look at the
Conclusions from this review…..