Samsung PM863 SATA 960GB Enterprise SSD Review

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.

If you are a Facebook user, like me and the Reynolds sibs, and
you reside in Europe – this is most probably where your data is click here.  Some
interesting Facebook statistics – Facebook has more than 1 Billion monthly
active users, it generates 1 Trillion page views per month and more than 219
Billion photos have been uploaded since launch – amazing!  Here is an
interesting video showing the remarkable scale of Facebook’s largest North
American data centre click
here.

Power Testing

We present our standard set of power consumption tests.

SNIA Write Saturation

Samsung PM863 SATA 960GB Enterprise SSD Review

 

 

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. 


4K Latency Test – Reads

Samsung PM863 SATA 960GB Enterprise SSD Review

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 boost in power consumption rises 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.

 


4K Latency – Writes

Samsung PM863 SATA 960GB Enterprise SSD Review

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.

 


4K Mixed Reads/Writes

Samsung PM863 SATA 960GB Enterprise SSD Review

Samsung
specifies average power consumption to be 3,800 mW for Writes and these results
fall within specification.

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

Samsung PM863 SATA 960GB Enterprise SSD Review

 

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

Samsung PM863 SATA 960GB Enterprise SSD Review

 

You can see that the Toshiba THNSNJ960PCSZ is more
efficient, but nevertheless this is a good result for the PM863.


Sequential Reads

Samsung PM863 SATA 960GB Enterprise SSD Review

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.

Samsung specifies average power consumption for Reads to be 3,000
mW and these results fall well within specification.

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

 

Samsung PM863 SATA 960GB Enterprise SSD Review

 

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).

Samsung PM863 SATA 960GB Enterprise SSD Review

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


Sequential Writes

Samsung PM863 SATA 960GB Enterprise SSD Review

 

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 –

Samsung PM863 SATA 960GB Enterprise SSD Review

 

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).

Samsung PM863 SATA 960GB Enterprise SSD Review

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


Power Up to Idle

Samsung PM863 SATA 960GB Enterprise SSD Review

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 rail and
peaks at just over 4,000 mW.

Power up to Idle first 150 mS

  

Samsung PM863 SATA 960GB Enterprise SSD Review

Here is a
closer look at the first 150 mS.  You can see that the PM863 kicks into life at
around 110 mS.

 


Idle

Samsung PM863 SATA 960GB Enterprise SSD Review

This test allows us to view the power consumption
characteristics when a drive is idling (powered up but with no IO activity). 

Samsung PM863 SATA 960GB Enterprise SSD Review

Here is a picture of the raw data values that were recorded.

Samsung PM863 SATA 960GB Enterprise SSD Review

Here are the statistics calculated for the recording.

The average power used when idling was 1,240 mW from the 5v rail,
which is excellent.


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.

Samsung specifies an UBER of 1 in 10^17 bits read
for the PM863.

Samsung PM863 SATA 960GB Enterprise SSD Review

The PM863 is warranted to support up to 1.33 Drive Writes
per Day (DWPD) over 3 years.

The PM863 includes sophisticated power failure support
(which ensures any in flight writes will be completed to NAND in the event of a
power failure) and end-to-end data protection.

 

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