Seagate 1200 400GB SAS Enterprise SSD Review

Please click here
to view or download a detailed introduction to Myce’s Enterprise Class Solid
State Storage (‘SSS’) Testing Methodology as a PDF.

Put briefly:

All testing
is performed on an OakGate Technology test unit

We perform
two sets of Performance Tests:

1.          
A full set of the Storage Network Industry Association’s (‘SNIA’) tests
with mandatory parameters, as specified in their Solid State Storage
Performance Test Specification Enterprise V1.0 – SNIA
SSS PTS Version 1.0
.

2.          
A set of tests, known as the ‘Myce/OakGate Full Characterisation Test
Set’, that provides readers with a fuller characterisation of the solution.

We also review other important factors such as Data
Reliability and Failover features.

A word about SNIA testing – before striking a partnership
with OakGate Technology I spent some time researching how I might implement
SNIA testing using freely available tools such as IOMeter and FIO.  I arrived
at the conclusion that whilst it was theoretically possible it was impractical. 
The reason for this is as without the automation offered by a test bench, such
as the OakGate Unit, the only way to meet the SSS PTS requirements is to run
the maximum number of test cycles and then to manually look back at the results
to determine when/if steady state has been achieved in the workload specific
test cycle, and then harvest the data from the qualifying Measurement Window. This
means that the test runs would always take a maximum elapsed time, and there
would be a great deal of human effort required to review, gather, and report
upon the data.  I empathise with, acknowledge, and respect the efforts of other
reviewers who endeavour to meet the SNIA’s principles in their testing – I am
privileged and thankful to be able to use a superb test bench which automates
the whole process and allows me to meet the SNIA’s specification in full.

Before we
move on, let’s remind ourselves of some basics –

When
reviewing the performance of an SSS solution there are three basic metrics that
we look at:

1.          
IOPS – the number of Input/Output Operations per Second

2.          
Bandwidth – the number of bytes transferred per second (usually measured
in Megabytes per second, ‘MB/s’)

3.          
Latency – the amount of time each IO request will take to complete
(usually, in the context of SSS solutions, measured in Microseconds, which are
millionths of a second).

It is true to say that IOPS and Bandwidth had all been
growing rapidly before the advent of SSS solutions, but Latency can only be significantly
decreased by eliminating mechanical devices, and thus Latency is the single
most important aspect that SSS solutions deliver to enhance performance.

Latency in a technical environment is synonymous with delay.
In the context of an SSS solution it is the amount of time between an IO
request being made, and when the request is serviced.

Bandwidth, also commonly referred to as ‘Throughput’, is the
amount of data that can be transferred from a storage device to a host, in a
given amount of time.  In the context of SSS solutions it is typically measured
in Megabytes per second (MB/s). 

A great enterprise SSS solution offers an effective balance
of all three metrics.  High IOPS and Bandwidth is simply not enough if Latency
(the delay in an IO operation) is too high. As we will see in the test results
presented below, as Latency increases IOPS will inevitably decrease.

Queue Depth is the average amount of IO requests
outstanding.  If you are running an application and the Average Queue Depth is
one or higher and CPU utilisation is low, then the application’s performance is
most probably suffering from a ‘Storage Bottleneck’.

Another important factor to remember is that SSS performance
is influenced by previous workloads, not just the current workload, and
especially by what has previously been written to the drive. As specified in
the SNIA SSS PTS the goal of all good Enterprise level testing is to provide
consistent circumstances, so that results can be compared fairly across
different SSS solutions – it is for this reason that all of our tests start
with a purge of the drive, so that it starts in a ‘Fresh Out of the Box’ (FOB)
state.  Most tests then have a pre-conditioning phase where the drive is put
into a ‘Steady State’ before the test phase begins. Put briefly, a ‘Steady
State’ is achieved when the performance of the drive no longer varies over time
and settles into a consistent level of performance for the workload in hand. You
can find a detailed explanation of ‘Steady State’ and how it is determined in
the SNIA tests in our Enterprise Testing Methodology paper, which can be viewed
or downloaded as a PDF by clicking here.

For interest, here are some generally accepted
assumptions that differentiate the use and therefore the approach to testing
Enterprise/Server and Consumer/Client SSS solutions:

Enterprise/Server SSS assumptions:

1.          
The drive is always full

2.          
The drive is being accessed 100% of the time (i.e. the drive gets no
idle time)

3.          
Failure is catastrophic for many users

4.          
The Enterprise market chooses SSS solutions based on their performance
in steady state, and that steady state, full, and worst case are not the same
thing

Consumer/Client SSS assumptions:

1.          
The drive typically has less than 50% of its user space occupied

2.          
The drive is accessed around 8 hours per day, 5 days per week, and
typically data is written far less frequently

3.          
Failure is catastrophic for a single user

4.          
The consumer/client market generally chooses SSS solutions based on
their performance in the FOB state

Comprehensive
power consumption testing is performed using Quarch hardware as documented here.

Esther Spanjer, Director, Enterprise
Business Development EMEA at Sandisk, said, ‘I am happy to commend Myce for
their high level of professionalism and cooperation during the review process’,
Ms. Spanjer added, ‘I wish them every success in their partnership with OakGate
Technology and their initiative to provide authoritative performance reviews
for the Enterprise Solid State Storage market’

Now let’s
head to the next page, to look at the results of our SNIA IOPS (Input/Output
Operations per Second) Test…..