SandForce TRIM Issue & Corsair Force Series GS (240GB) Review
by Kristian Vättö on November 22, 2012 1:00 PM ESTRandom Read/Write Speed
The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews. Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see).
We perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time. We use both standard pseudo randomly generated data for each write as well as fully random data to show you both the maximum and minimum performance offered by SandForce based drives in these tests. The average performance of SF drives will likely be somewhere in between the two values for each drive you see in the graphs. For an understanding of why this matters, read our original SandForce article.
Random read speed has never been SandForce's strength and the Force GS is no exception. Real-time compression doesn't provide much benefit to read performance because reading from NAND has always been much faster than programming. Presumably SandForce's third generation controllers (SF-3000) will address random read and write performance, although it's way too early to tell how big of improvements we should expect.
Random write performance is exceptionally low. At queue depth of 3 (the first random write graph), the Force GS manages to stay roughly on-par with other SF-2281 based SSDs, but at queue depth of 32 there is a more noticeable difference. While we are only talking about a difference of a few percents, it's still surprising that the Force GT doesn't achieve speeds similar to other SF-2281 SSDs.
Sequential Read/Write Speed
To measure sequential performance we ran a one minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length.
Sequential performance is typical SandForce. With highly compressible data, SandForce SSDs are still the fastest in sequential write speed, although OCZ Vertex 4 is getting very close.
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bradcollins - Thursday, November 22, 2012 - link
One question, all of the tests at Anandtech for Sandforce performance after being hammered for a period of time are always over the entire drive. Do the drives maintain their performance if the random writes are only over 50% or 75% of the LBA's on the drive? Very few people actually fill up their SSD so I wonder if it is a truely relevant test?Impulses - Wednesday, November 28, 2012 - link
You will always eventually use all of your SSD, wear leveling algorithms will spread data across all NAND packages... A certain portion will always be marked "empty" if you haven't filled it to capacity, but that space has been issued and it's subject to the performance degradation conditions AT tests for.Bullwinkle J Moose - Thursday, November 22, 2012 - link
Time for an article on Cache Analysis?It looks to me as though the 1GB Dram Cache on the Intel DC S3700 is mainly responsible for smoothing out those peaks and valleys to deliver "Consistant" performance across the drive
As for trim.....
It's time to start with a fresh perspective on SSD's
Bullwinkle J Moose - Thursday, November 22, 2012 - link
I know Intel claimed otherwise on the dram usage, but I don't buy itSounds more likely they are just sending the competition on a wild goose chase
Bullwinkle J Moose - Thursday, November 22, 2012 - link
Reread DC S3700 review again256MB of the 1GB is used for cache
OK, my bad
Bullwinkle J Moose - Thursday, November 22, 2012 - link
DohIf I read it 5 more times I'll get it right eventually
extide - Saturday, November 24, 2012 - link
If it were that easy, don't you think other guys would have drives like the 3700 out?Kristian Vättö - Friday, November 23, 2012 - link
The problem with caching in general is that there is no good way to test how much write/read caching the drive is doing. All we got is what manufacturers tell us, which may or may not be accurate.mayankleoboy1 - Friday, November 23, 2012 - link
With each review, Samsung 840Pro looks better and better.JellyRoll - Friday, November 23, 2012 - link
This information has been already hashed over by several sites, in particular TweakTown. They have been educating the public for months about the lack of TRIM with Sandforce SSDs.Other sites have also noticed the read degradation, and commented on it ad nauseum.