TEST SETUP AND METHODOLOGY
In testing the Samsung 845DC PRO, along with all enterprise drives, we focus on long term stability. In doing so, we stress products not only to their maximum rates, but also with workloads suited to enterprise environments.
We use many off-the-shelf tests to determine performance, but we also have specialized tests to explore specific behaviors we encounter. With enterprise drives, you will see that we do not focus on many consumer level use-cases.
Our hope is that we present tangible results that provide relevant information to the buying public.
To specifically measure latency, we use a series of 512b, 4K, and 8K measurements. At each block size, latency is measured for 100% read, 65% read/35% write, and 100% write/0% read mixes.
This is very low latency. We normally don’t see anything in that range on SATA devices, especially for writes.
Even more impressive is the maximum latency. Almost off of our results were under 10ms, with maximum read latency under 2ms.
ADVANCED WRITE TESTING
As we talked about in our Micron P400m SSD Review, SSDs have different performance states. Since the Samsung 845DC PRO is an enterprise SSD, we will focus on steady state performance. With the following tests, we stressed the drive using random 4KB write workloads across the entire span for at least 24 hours. This is more than enough to achieve steady state. The following graph is showing the latency and IOPS across an 11 hour span.
These were the sort of results that we were hoping for. Not only did we blow by the 50K IOPS number from the datasheet, the 845DC PRO did it consistently. In our per minute average, we did not see more than a 500 IOPS swing across 11 hours.
Zooming in on the last hour shows results that do not disappoint. We are still seeing the 50K IOPS and a very tight grouping of data. Almost all of the datapoints are over 50K IOPS, with just a few falling short of that number. For a 6Gbps SATA device, this is tops for a standard configuration. We have reviewed drives from Intel, Micron and SMART that have posted IOPS in the mid-30K IOPS range, but never 50K. In order to get that level of write IOPS, you need either a PCIe or 12Gbps SAS interface. In every single one of those cases, you are paying way more than $2/GB.