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

Power Consumption and Data Reliability

Power Consumption

I believe most people know that data centres are already one
of the major consumers of electricity in the industrialised world; indeed it is
estimated that currently 2% of all electricity consumption goes into IT
applications.  According to the European Union the energy consumption of data
centres was 46 Terawatt hours in 2006 and is set to rise to 93 TW hrs by 2020. This
is equivalent to one hundred million 100W light bulbs burning 24 hours a day,
365 days a year.

Typically 40% of the power consumed by data centres is for
the IT load and 35% is for cooling the system.  Generally speaking, if a drive
consumes more power it will produce more heat – so power consumption is indeed
a double edged sword.  It is no surprise then that a significant proportion of
a data centre’s power consumption goes on servers.  I understand cloud based
applications, such as Facebook, are the primary cause of the growth in servers
and the demand for storage space.

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Power Testing

We present our standard set of power consumption tests.

SNIA Write Saturation

Power Efficiency Mode – Single Port

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

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This test allows us to observe the power consumption
characteristics as the drive passes from a fresh ‘out of the box’ state to one
where blocks must first be cleaned before they can be written to.  It also
allows us to form a view on the amount of power that is being consumed by the
cleaning of the blocks (for 4K random writes). We can see a slight increase in
power consumption after hitting the write cliff at around round 50, but roughly
speaking, by round 140 we can see that around 6,700mW is required to sustain
around 95,000 IOPS whereas before the write cliff, the same level of power was
sustaining around 180,000 IOPS. Thus we can deduce that roughly 85,000/180,000
of the 6,700mW (i.e. roughly 47% of the power) is consumed by housekeeping.

Maximum Performance Mode – Single Port

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

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In Maximum Performance Mode we can see the increase in power
consumption and the commensurate increase in IOPS. By Round 150, we can see
that roughly speaking around 7,700mW is required to sustain 125,000 IOPS.  Thus
we can deduce that roughly 55,000/180,000 of the 7,700mW (i.e. roughly 30% of
the power) is consumed by housekeeping.

 


4K Latency Test – Reads

Power Efficiency Mode – Single Port

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This test allows us to observe how power consumption
characteristics vary as the demand for random 4K reads (in terms of IOPS) is
increased.  You can see that the demand for power increases gradually and in a
linear fashion. 

As the increase in power consumption increases more slowly
than the increase in IOPS we know intuitively that the sweet spot in regard to
IOPS per mW is at the highest IOPS level.

Power Efficiency Mode – Dual Port

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In Dual Port operation we can see that both the maximum
level of power consumed and level of IOPS achieved has increased, we will look
at the IOPS per mW being achieved shortly.

 

Maximum Performance Mode – Single Port

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

In Maximum Performance/Single Port we can see that the
maximum level of power consumption and the maximum level of IOPS achieved has
increased over Power Efficiency mode.  We will look at the level of efficiency,
in terms of IOPS per mW shortly.

 

Maximum Performance Mode – Dual Port

 

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

Again, in Dual Port operation we see both the power
consumption and IOPS achieved increase over that seen for single port
operation.


4K Latency – Writes

Power Efficiency Mode – Single Port

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

This test allows us to observe how power consumption
characteristics vary as the demand for random 4K writes (in terms of IOPS) is
increased.  You can see that the demand for power increases gradually and in a
linear fashion.

As the increase in power consumption increases more slowly
than the increase in IOPS we know intuitively that the sweet spot in regard to
IOPS per mW is at the highest IOPS level.

 

Power Efficiency Mode – Dual Port

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

We see little or no difference in power consumption for dual
port mode when compared to that for Power Efficiency/Single Port mode but then
we see no difference in IOPS either.

 

Maximum Performance Mode – Single Port

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

We see an increase in both power consumption and IOPS
achieved when compared to that for Power Efficiency Mode.  We’ll take a look at
efficiency, in terms of IOPS per mW shortly.

 

Maximum Performance Mode – Dual Port

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

We see little or no difference in power consumption or IOPS
when compared to Maximum Performance/Single Port operation.

 


4K Mixed Reads/Writes

Power Efficiency Mode – Single Port

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

Power Efficiency Mode – Dual Port

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

This test allows us to see how power consumption characteristics
vary when performing 4K random reads and writes with different combinations of
read/write % and queue depth.  As would be expected, you can see that as one
increases the % of writes the power consumption increases.

Maximum Performance Mode – Single Port

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

Maximum Performance Mode – Dual Port

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

As could be expected we see an increased level of power
consumption between the so called Power Efficiency and Maximum Performance
modes but we don’t see much difference between the single and dual port operations
in each mode.  So now let’s have a look at whether there is a difference in
efficiency (in terms of IOPS per mW) for each mode.

We have then taken the data to calculate the IOPS per mW for
each combination, as follows –

Single Port – Power Efficiency and Maximum Performance
Modes

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

Here, you can see that in Single Port mode that there is not
a great difference in efficiency between Power Efficiency (9W) and Maximum
Performance (12W) modes.  Indeed you can see that the Maximum Performance mode
is more efficient for the higher Write percentages.

Dual Port – Power Efficiency and Maximum Performance
Modes

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

You can see that Dual Port operation is more efficient than
Single Port where the Write% is low and the Dual Port operation’s greater
ability to perform random reads comes into play.

You can also see that Maximum Performance mode is slightly
more efficient for the higher Write percentages.

We can conclude that for Random IO traffic Maximum
Performance Mode, both in single port and dual port operation, is actually
slightly more efficient than Power Efficiency Mode as measured by IOPS per mW. 
There is though one important factor that we have not measured in our testing,
which is the heat generated in both modes.  I suspect that the drive will run
significantly cooler in Power Efficiency mode and that this is the real benefit
of running in power efficiency mode.

Now, let’s compare these results to the best results we have
seen from a drive prior to this review, which are for another Toshiba drive the
THNSNJ960PCSZ –

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

 

You can see that the PX04SMB is more efficient in dual port
operation and more efficient for the higher Write percentages even in single
port operation. So the PX04SMB takes over as the most efficient drive we have
tested for 4K Random IOs.


Sequential Reads

Power Efficiency Mode – Single Port

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

Power Efficiency Mode – Dual Port

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

Maximum Performance Mode – Single Port

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

 

Maximum Performance Mode – Dual Port

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

This test allows us to see how power consumption
characteristics vary when performing sequential reads with different
combinations of IO Size and queue depth.  As might be expected, the power
consumption increases as the MB/s increases.

We have then
used this data to calculate the MB/s per mW as follows –

Single Port – Power Efficiency and Maximum Performance
Modes

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

You can see that there is little or no difference in
Sequential Read efficiency between Power Efficiency (9W) and Maximum
Performance (12W) Modes in Single Port operation.

Dual Port – Power Efficiency and Maximum Performance
Modes

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

Again in Dual Port operations, we can see that there is
little difference in efficiency for Sequential Reads between Power Efficiency
and Maximum Performance Modes but if anything Maximum Performance mode is more
efficient.

The MB/s per mW results can then be compared to those for
the Toshiba THNSN960PCSZ (the drive with the best power consumption results,
that has previously been subjected to our Enterprise Power Tests).

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

You can see that the THNSNJ960PCSZ is slightly more
efficient for Sequential Reads.


Sequential Writes

Power Efficiency Mode – Single Port

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

Power Efficiency Mode – Dual Port

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

 

Maximum Performance Mode – Single Port

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

 

Maximum Performance Mode – Dual port

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

 

This test allows us to see how power consumption
characteristics vary when performing sequential writes with different
combinations of IO Size and queue depth.  As might be expected, the power
consumption increases as the MB/s increases.

 

We have then used this data to calculate the MB/s per mW as
follows –

Single Port – Power Efficiency (9W) and Maximum
Performance (12W) Modes

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

You can see that in Single Port operation Maximum
Performance mode is more efficient for Sequential Writes. 

Dual Port – Power Efficiency (9W) and Maximum Performance
(12W) Modes

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

You can see here that for Dual Port operation Maximum
Performance mode is marginally more efficient for Sequential Writes.

 

The MB/s per mW results can then be compared to those for
the Toshiba THNSN960PCSZ (the drive with the best power consumption results,
that has previously been subjected to our Enterprise Power Tests).

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

You can see that the THNSNJ960PCSZ is slightly more
efficient for Sequential Writes.


Power Up to Idle – Power Efficiency Mode and Maximum
Performance Modes

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

You can see that the shape of the Power on to Idle power
consumption profile looks identical for both modes

This test allows us to see the shape of the power demand profile
as a drive is powered up. It also allows us to see the peak level of current demanded
to kick the drive into life.

As you can see, power is drawn from only the 5v and 12v rails
and peaks at around 3,000mS.

Power up to Idle first 150mS – Power Efficiency and
Maximum Performance Modes

  

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

Here is a
closer look at the first 150 mS.  You can see that for Power Efficiency Mode the
drive initially comes to life between 50 – 100 mS. Interestingly for Maximum
Performance Mode nothing much has happened in the first 150mS.

So for Maximum
Performance Mode let’s look at the first 300mS –

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

You can see that in Maximum Performance Mode things start to
happen a moment later at around 200mS but that the shape of the power up profile
is the same as for Power Efficiency Mode.    


Idle – Power Efficiency and Maximum Performance Modes

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

This test allows us to view the power consumption characteristics
when a drive is idling (powered up but with no IO activity).  You can see that
there is no difference between Power Efficiency and Maximum Performance modes.

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

Here is a picture of the raw data values that were recorded
in Power Efficiency Mode.

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

Here are the statistics calculated for the recording taken
in Power Efficiency Mode.

The average power used when idling was 3,491 mW from the 12v
rail (and negligible from the 5v rail).  This does not compare well with
Toshiba’s specification that states that typical power consumption is 3.2W, as
we are exceeding this with 3.491W when idling.  I suspect this is just a simple
mistake on Toshiba’s part as their usual approach to specifications is to
understate them.


Data Reliability

The ‘Unrecoverable Bit Error Rate’ (UBER),as defined by
JEDEC, the global leader in developing open standards for the microelectronic
industry, is a metric for data corruption rate equal to the number of data
errors per bit read after applying any specified error correction method. UBER
= number of data errors / number of bits read.  JDEC specifies that the maximum
error rate allowable for an Enterprise level SSS solution is one error in every
10^16 bits read.

Toshiba specifies an UBER of 1 in 10^17 bits read
for the PX04SMB series.

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

The PX04SMB160 1600GB is warranted to support up to 10 Drive
Writes per Day (DWPD) over 5 years.

The PX04SMB series includes sophisticated power failure
support and end-to-end data protection.

 

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

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