Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review – The SAS Awakens

Myce/OakGate 4K Read and Write Latency Tests

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.

Please note that throughout the Myce/OakGate tests we are
showing results for each combination of Power Mode (Power Efficiency and
Maximum Performance) and Single and Dual Port operation.  At the end of each
test we also present a basis for comparing the four sets of results.

Firstly, here are the results for the initial
Pre-Conditioning step (4K Random Writes) –

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Myce/OakGate 4K Read and Write Latency Tests
Preconditioning – Power Efficiency Mode – Single Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

 

We can see the ‘write cliff’ at around 3,200 Seconds.  The
drive then immediately settles into an excellent steady state performance of 95,000
IOPS.  The other remarkable aspect of this result is the apparent consistency
of performance shown by the tight distribution of the IOPS time line
(especially after the write cliff occurs).  The only other drive I have seen
that approaches this level of consistency was the original Smart/Sandisk
Optimus.

Let’s have a closer look by zooming in on the IOPS time line
–    

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Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see what seems to be a characteristic repetition with
a slight dip in IOPS occurring every 40 seconds or so.

 

Myce/OakGate 4K Read and Write Latency Tests
Preconditioning – Power Efficiency Mode – Dual Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

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In Power Efficiency/Dual Port mode we don’t see any increase
in Steady State IOPS, but we do see an increased level of inconsistency.  

Myce/OakGate 4K Read and Write Latency Tests
Preconditioning – Maximum Performance Mode – Single Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

In Maximum Performance/Single Port mode we see the drive
settle into a remarkably impressive Steady State of 125,000 IOPS and again we
see a remarkable level of consistency.

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Myce/OakGate 4K Read and Write Latency Tests
Preconditioning – Maximum Performance Mode – Dual Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

…and again we see that there is no increase in random
write performance for dual port operation but there is an increased level of
inconsistency.

 

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4K Latency Read Test

Myce/OakGate 4K Read Latency Test – Power Efficiency Mode
– Single Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the drive can no longer meet the increase in
IOPS demand beyond 150,000 IOPS although the IOPS response level does continue
to increase beyond 190,000.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that read latency remains below 120 Micro Seconds
all the way up to a demand and response of 150,000 IOPS.  This is an outstanding
result. 

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that up to a demand of 150,000 IOPS there are no
significant Maximum Latency spikes – A remarkable result.

Let’s have a close look at the distribution of the Latency
results at the 120,000 IOPS level –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

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.

We can see that 99.999% of the Latency values are <= 300
Microseconds – the quality of service as measured in this test is the best I
have seen!


Myce/OakGate 4K Read Latency Test – Power Efficiency Mode
– Dual Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

It is important to note that in dual port operation the way
that the OakGate test unit caps the demand in IOPS is applied to each port. 
So, for example at a demand of 20,000 IOPS we see a response of 40,000 IOPS as
both ports meet the demand of 20,000.

We can see that the drive continues to meet the demand in
IOPS up to a total demand of 200,000 IOPS but the level of IOPS response increases
further to a maximum of around 290,000 (when 150,000 IOPS is being demanded of
each port).  So here we see that Dual Port operation gives a significant
increase in Random Read performance.

The OakGate test unit also enable us to look at the
performance of the individual ports in a multi-port operation.  So let’s have a
look –

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the distribution of IOs to each port is indentical
up to a demand of 100,000 IOPS per port, but beyond this the distribution
varies somewhat.  An even distribution is what we look for in multiport
operations and this is an excellent result.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the Read Latency remains below 120 Micro
Seconds all the way up to a demand of 130,000 IOPS to each port.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see clearly that there are no Maximum Latency spikes
until the drive’s maximum IOPS response is exceeded.

 

Let’s have a close look at the distribution of the Latency
results at the 140,000 IOPS level of demand to each port –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that 99.999% of the Latency values are <= 900
Microseconds (0.9 Milliseconds). Another excellent result!


Myce/OakGate 4K Read Latency Test – Maximum Performance
Mode – Single Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that it Maximum Performance/Single Port mode the
drive continues to meet the increase in demand all the way up to 200,000 IOPS –
outstanding!

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that Latency remains below 150 Micro Seconds all
the way up to the 190,000 IOPS level!

We can see a few max latency peaks –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

Let’s have a close look at the distribution of the Latency
results at the 50,000 IOPS level (at one of the peaks) –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that 99.9% of the Latency values are <= 160
Micro Seconds (0.16 Milliseconds), so the quality of service is outstanding.


Myce/OakGate 4K Read Latency Test – Maximum Performance
Mode – Dual Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the drive continues to meet the increase in
demand all the way up to a total demand of 320,000 IOPS (with a demand of
160,000 IOPS to each port).

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the IOs are distributed evenly to each port
until the demand exceeds 160,000 IOPS per port.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the Read Latency does not exceed 200 Micro
Seconds until the drive’s maximum IOPS level is exceeded.

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that there are no Maximum Latency spikes to speak
of until the drive’s maximum IOPS level is exceeded.  Let’s have a look at the
worst case peak at 150,000 IOPS –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that 99.999% of values are <= 2,050 Micros
Seconds (2.05 Milliseconds).  This is an excellent result.

 


4K Latency Write Test

Myce/OakGate 4K Write Latency Test – Power Efficiency
Mode – Single Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that in Power Efficiency/Single Port mode the
drive continues to meet the increase in demand up to a level of 90,000 IOPS and
that the maximum response is 95,000 IOPS.   

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

 

Here we can see that Average Write Latency stays below 50 Micro
Seconds all the way up to a demand of 90,000 IOPS – very impressive!

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that there are no Maximum Latency peaks at all,
until a level of 30,000 IOPS is exceeded.

Now let’s have a look at the distribution of the Latency
Values at the 80,000 IOPS Mark –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that 99.9% of the Latency Values are <= 480 Micro
Seconds.  There is only a very small number of outliers. This is a very
impressive, outstanding result.


Myce/OakGate 4K Write Latency Test -Power Efficiency Mode
– Dual Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that there is no increase in IOPS performance in
Dual Port mode as with a demand of 50,000 IOPS to each port the response is
95,000 (the same as for Single Port).

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the IOs are distributed evenly to each port
until the maximum IOPS response level is exceeded.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

 

We can see that the Latency values remain below 100 Micro
Seconds until a demand of 40,000 IOPS to each port is exceeded.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the maximum latency values are somewhat
worse than they are for single port mode.

Now let’s have a look at the distribution of the Latency
Values at the demand level of 40,000 IOPS to each port –

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

You can see that 99% of the Latency Values are <= 80 Micro
Seconds and that there is a relatively small number of outliers.


Myce/OakGate 4K Write Latency Test -Maximum Performance
Mode – Single Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

You can see that in Maximum Performance/Single Port mode the
drive continues to meet the increase in demand up to a level of 120,000 IOPS
and that the maximum response is 125,000 IOPS.    

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

You can see that the Latency Values remain at <= 50 Micro
Seconds all the way to the 120,000 IOPS level of demand. Outstanding!

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

So Maximum Write Latencies for Maximum Performance mode are
similar (though a bit higher) than for Power Efficiency mode.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

It is interesting to compare these results to those seen for
the drive in Power Efficiency/Single Port mode, as follows –

                                      Power
Efficiency/Single Port               Maximum Performance/Single Port

                                      at 80,000 IOPS                                  at
100,000 IOPS

99.999%                                  7,490 uS                                            9,110
uS

99.9%                                      480 uS                                               1,160
uS

99%                                         60 uS                                                 130
uS

95%                                         40 uS                                                 60
uS

We can see that although a significantly higher IOPS level
is achieved in Maximum Performance mode (125,000 IOPS vs. 95,000 IOPS) the Quality
(consistency) of Service is somewhat worse for Maximum Performance mode.


Myce/OakGate 4K Write Latency Test -Maximum Performance
Mode – Dual Port

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

Just as for Power Efficiency mode – we don’t see an increase
in Random write IOPS for dual port operation in Maximum Performance mode.

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

 

Toshiba PX04SMB160 SAS 1600GB Enterprise SSD Review - The SAS Awakens

We can see that the Quality of Service is slightly worse in
dual port operation.

 

Now let’s head to the next page, to look at the results
for the Myce/Oakgate Reads and Writes Tests…..

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