Sequential Performance – HDTach, HDTune, File Copy, YAPT (sequential)
We have shifted over to combining our results into two groupings for consumer reviews. First up is sequential performance:
HD Tach will test the sequential read, random access and interface burst speeds of your attached storage device (hard drive, flash drive, removable drive, etc). All drive technologies such as SCSI, IDE/ATA, 1394, USB, SATA and RAID are supported. HDTach tests sequential performance by issuing reads in a manner that was optimized more for HDD access, but this unique method has proven useful in evaluating the sequential response time of SSDs. The accesses are relatively small in size (2k), and are issued with a single working thread (QD=1). The end result is that devices with relatively IO high latency will not reach their ultimate rated speed.
Nothing out of the ordinary here. Samsung SSDs have always been excellent at QD=1 performance, and can do so even with 2TB of data written in sequential 2KB chunks. Speeds are even *up* slightly compared to the previous 1TB capacities of the same models!
HDTune tests a similar level of features as compared with HDTach, but with a different access pattern. Thus provides us with an additional set of benchmark numbers to compare between storage configurations. CPU utilization has proven negligible with modern processing horsepower, and is no longer included. Additionally, we do not include write performance due to HDTune's write access pattern not playing nicely with most SSDs we have tested it on.
We have HDTune configured to perform large block reads, but the test is performed after the HDTach run (small sequential writes). Despite this, the 2TB models are still able to saturate the SATA 6GB/sec link. Fun fact: even at speeds fully saturating SATA 6Gb/sec, it takes over half an hour to fully read (or write) a 2TB SSD!
PCPer File Copy Test
Our custom PCPer-FC test does some fairly simple file creation and copy routines in order to test the storage system for speed. The script creates a set of files of varying sizes, times the creation process, then copies the same files to another partition on the same hard drive and times the copy process. There are four file sizes that we used to try and find any strong or weak points in the hardware: 10 files @ 1000 MB each, 100 files @ 100 MB each, 500 files @ 10 MB each and 1000 files at 1 MB each.
File creations are just that much faster than prior models, with that advantage lessened when writing batches of smaller files.
Yet another round of improvements in our file copy testing. Samsung appears to have made some specific optimizations to the 850 EVO in 2TB form, as 2.9 seconds is the fastest time we've clocked moving 1,000 1MB files within any single SATA SSD! I suspect this tuning may come with a catch – stay tuned to find out if one exists.
YAPT (yet another performance test) is a benchmark recommended by a pair of drive manufacturers and was incredibly difficult to locate as it hasn't been updated or used in quite some time. That doesn't make it irrelevant by any means though, as the benchmark is quite useful. It creates a test file of about 100 MB in size and runs both random and sequential read and write tests with it while changing the data I/O size in the process. The misaligned nature of this test exposes the read-modify-write performance of SSDs and Advanced Format HDDs.
No surprises with YAPT. All SSDs running at expected speeds here, with no drops noted from the largest capacity 850 EVO and Pro.