Intel DC P4510 8TB NVMe Enterprise SSD Review

Posted 13 August 2018 01:31 CET by Jeremy Reynolds

Myce/OakGate 4K Read and Write Latency Tests and Quality of Service

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. We also use the detailed Latency results for each IOPS level to extract Quality of Service data.  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 these tests were run at a Queue Depth of 256.

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

Myce/OakGate 4K Read and Write Latency Tests Preconditioning –

 

Please note that the 4K Random Writes were preceded by a pre-fill step, which performed 128K sequential writes to twice the drive’s capacity (to facilitate the achievement of a steady state). 

 


4K Latency Read Test

Myce/OakGate 4K Read Latency Test

You can see that the increase in IOPS demand can no longer be met beyond 630,000 IOPS.

For interest, let’s have a look at the 640,000 IOPS demand point more closely –

You can see that the Read IOPS is peaking at around 630,000.

 

Here you can see that Power consumption gradually increases as the IOPS demand increases.

 

We can see that read latency remains below 210 microseconds all the way up to its maximum IOPS level. This is an outstanding result. 

 

There are no notable Maximum Latency spikes.

For interest let’s a close look at the distribution of the Latency results at the 400,000 IOPS level –

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 99.9% of the Latency values are <= 290 Microseconds and there are remarkably few outliers – the Quality of Service as measured in this test is outstanding.


4K Latency Write Test

Myce/OakGate 4K Write Latency Test

 

You can see that the increase in IOPS demand can no longer be met beyond 150,000.

For interest, let’s have a look at the 160,000 IOPS demand point more closely –

 

Interestingly, the drive sustains the demand of 160,000 for the first 55-60 seconds before it falls back to around 150,000.

For interest, let’s have a look at the 170,000 IOPS demand point –

You can see that the drive is now consistently falling short of the demand.

 

Here you can see that power consumption increases gradually as the IOPS demand increases.

Here we can see that Average Write Latency stays below 50 microseconds all the way up to a demand of 120,000 – an outstanding result.

 

There are no notable Maximum Latency peaks.

So let’s have a look at the distribution of the Latency Values at the 100,000 IOPS level –

We can see that 99.9% of the Latency Values are <= 380 Microseconds, and there is only a relatively small number of outliers. This is an outstanding result.  


Quality of Service

Quality of Service (QoS) of an SSD consists of the predictability of low latency (and consistency of high IOPS) while servicing a particular IO workload. This means the latency needs to be within a specified range without having unexpected outliers.

QoS of an SSD is most often measured as the latency achieved for a workload for a specified percentage of the time.  An SSD that has a lower latency for a percentage will exhibit a superior level of performance predictability. QoS is most often measured (and specified by Manufacturers) for 4K Random Reads and Writes at a Queue Depth of 1 and/or 32.

Commonly the cause of an outlier is the background tasks performed by an SSD’s controller, such as required to reclaim spare space and to perform wear levelling, which may consume much of an SSD’s bandwidth temporarily starving host IOs thus causing significant latency variation.

It is also important to note that QoS will vary depending upon the level of IOs (IOPS) being serviced. Not surprisingly, as the IOPS level increases the QoS generally drops (though there could be exceptions to this, for example, if an SSD’s controller initiates background processes when it is less busy the occurrence of outliers may actually be greater at lower levels of demand)

Let’s have a closer look at the Quality of Service delivered by the Intel DC P4510.

From the above test for 4K Random Reads I have extracted the 95th, 99th, 99.9th and 99.999th percentile Latency values for levels of IOPS demand in the range of 50,000 through 600,000 IOPS, in increments of 50,000 IOPs, and charted them below.  The Latency Value (percentile rank) for the 95th percentile is the Latency that 95% of all IOs fall within (and similarly for the 99th, 99.9th and 99.999th percentiles).  The percentiles are a measure of the drives consistency in the delivery of its performance.  Here are the results for Random 4K Reads –   

 

The Quality of Service at the given IOPS levels can then be compared to that achieved by other drives.  For example, here are the values for the outstanding Micron 9100 Max –

Please note that the Micron 9100 Max meets a higher level of IOPS demand, up to 750,000

Let’s directly compare the 99.999% and 99.9% percentiles for the Intel DC P4510 and Micron 9100 Max –

You can see that for the most demanding 99.999% percentile the Intel DC P4510 is higher (worse) than the Micron 9100 Max.

Here you can see that at the 99.9% percentile the Intel DC P4510 is consistently lower (better) than the Micron 9100 Max.

 

Similarly, for 4K Random Writes I have extracted the 95th, 99th, 99.9th and 99.999th percentile Latency values for the range of 50,000 through 150,000 IOPS, in increments of 50,000 IOPs, and charted them as follows –

These are excellent results.

Now, let’s compare them to the results that we recorded for the Micron 9100 Max –

Please note that the Micron 9100 Max meets a higher level of Write IOPS demand, up to 300,000.

Let’s directly compare the 99.999% and 99.9% percentiles for the Intel DC P4510 and Micron 9100 Max –

You can see the Micron 9100 Max is consistently lower than the Intel DC P4510.  

Again, you can see the Micron 9100 Max is consistently lower than the Intel DC P4510.

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