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

SNIA Write Saturation Test

This test performs random 4K writes.

The objective of this test is to observe the time evolution of
the drive’s performance, as a function of time, from a ‘factory fresh’, ‘fresh
out of the box’ (‘FOB’) state.  When a drive is in a FOB state (e.g. after it
has been purged by, for example a SATA Secure Erase or SCSI Format), we can
expect an initial period of time when writes can easily be accommodated by
clean/empty blocks, but once all of the clean blocks have been written to once
and the drive’s controller must first clean blocks (with erase write
operations) before it can write new data, then we can expect a slow down.  The
slow-down is usually quite dramatic and is commonly referred to as the ‘write
cliff’. 

The Write Saturation Test is
easy to run as it requires no steady state determination – it can be easily run
in freely available software, such as IOMeter.

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Here are the results –

SNIA Write Saturation Test
– Power Efficiency Mode – Single Port

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

 

You can see here a distinctive write cliff at around Round 50
followed by a very impressive steady state of 95,000 IOPS.  We will look at the
Quality of Service (consistency of performance) being achieved in the
Myce/OakGate tests later in this review. 

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Note that the test was halted, as specified in the SNIA SSS
PTS, when 4 x the User Capacity had been written to the drive.   

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

 

You can also see that the latency graph line is a mirror
image of the IOPS graph line.


SNIA Write Saturation Test – Maximum Performance Mode –
Single Port

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

You can see here that the write cliff is again encountered
at around Round 50, which shows that there is little or no difference in the
speed that fresh blocks are written to between the two power modes.  The
Performance Mode sees an outstanding steady state of 125,000 IOPS, which is a
significant step up of 30,000 IOPS compared to the level achieved in Power Efficiency
mode.

 

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

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Now let’s
head to the next page, to look at the SNIA Throughput Test…..

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