These tests steadily increase the random 4K IO demand in
terms of IOPS, and report the drive’s response in terms of Average IOPS, Average
Latency and Maximum Latency. It is designed to show a drive’s maximum IOPS
capability and report the all important Latency numbers for each level of IOPS
demanded. The Maximum latency numbers give us an insight into the occurrence
of Latency peaks that could cause an unexpected response from time to time.
Here are the results –
Please note that this test was run at a queue depth of 32
and this is why Intel’s specified IOPS performance level is not being
achieved. When run at a queue depth of 64 the drive exceeds Intel’s specs!
Please see my upcoming review of the DC P3700 800GB
Firstly, here is a graph showing the result for the initial
Pre-Conditioning step (4K Random Writes) –
4K Latency Read Test
Please note that we have changed the normal scale that we
use here so that results are recorded for increments of 10,000 IOPS (We
normally record in increments of 1,000 IOPS but this was considered impractical
for a drive that can exceed a level of 250,000 IOPS)
You can see that the drive can no longer meet the increase
in IOPS demand at around 270,000 IOPS.
You can see a gradual increase in read latency up to the
maximum IOPS mark. The Read Latency results are excellent.
You can see that there are some max latency spikes.
Let’s have a close look at the distribution of the Latency
results at the 150,000 IOPS level (at one of the spikes) –
As this is the first time in this review, that we are
looking at a High Resolution Latency Histogram, here’s an explanation – The X
axis to the left is the count of the IOs in the observation period (in a Round)
that had a Latency of the value along the Y axis (please note that the X axis
is logarithmic to allow the low order counts of the huge number of IOs that
have been measured to be visible); the Y axis is the Latency value measured in
Microseconds; The X axis to the right is the % of the Total IOs observed that
have a Latency <= to a given Latency value; the rate of getting to 100% is
highlighted by the red graph line.
You can see that 99% of the Latency values are <= 190 Microseconds
and there are relatively few outliers, so the quality of service is excellent.
4K Latency Write Test
You can see here that the Intel P3700 starts failing to meet
the increase in IOPS demand at just above 150,000. An awesome result!
Here we can see that Average Write Latency stays below 30 microseconds
until a demand of 140,000 IOPS. Another awesome result!
The maximum write latency results are relatively high
(perhaps this is something Intel should take a closer look at :o) ).
So let’s have a look at the distribution of the Max Latency
Values at the 140,000 IOPS Mark –
You can see that 95% of the Latency Values are <= 70
microseconds. This is an excellent result.
Now let’s head to the next page, to look at the results
for the Myce/Oakgate Reads and Writes Tests…..