OWC Mercury Extreme Pro 6G SSD Review (120GB)
by Anand Lal Shimpi on May 5, 2011 1:45 AM ESTTRIM Performance
In practice, SandForce based drives running a desktop workload do very well and typically boast an average write amplification below 1 (more writes to the device than actual writes to NAND). My personal SF-1200 drive had a write amplification of around 0.6 after several months of use. However if subjected to a workload composed entirely of incompressible writes (e.g. tons of compressed images, videos and music) you can back the controller into a corner.
To simulate this I filled the drive with incompressible data, ran a 4KB (100% LBA space, QD32) random write test with incompressible data for 20 minutes, and then ran AS-SSD (another incompressible data test) to see how low performance could get:
| OWC Mercury Extreme Pro 6G 120GB - Resiliency - AS SSD Sequential Write Speed - 6Gbps | |||||
| Clean | After Torture | After TRIM | |||
| OWC ME Pro 6G 120GB | 163.6 MB/s | 62.7 MB/s | 104.9 MB/s | ||
| OCZ Vertex 3 120GB | 162.1 MB/s | 38.3 MB/s | 101.5 MB/s | ||
You'll notice that the After Torture number is better than the 120GB Vertex 3. Remember that the OWC drive's 4KB random write performance is capped, so the drive simply doesn't get as fragmented in 20 minutes as the Vertex 3 - the behavior of the two drives would be the same if we wrote the same physical amount of data to each drive. Neither drive is quite as resilient as the 240GB version. If you are using your SSD primarily for incompressible data (images/videos/music) storage and manipulation then you're probably better off with an Intel SSD 510 or Crucial m4.
Power Consumption
Power consumption is a bit higher on the OWC drive than the Vertex 3, perhaps the firmware differences extend beyond just 4KB random write performance:
Final Words
With the exception of the (temporary?) 4KB random write cap and slightly higher power consumption, OWC's Mercury Extreme Pro 6G is a dead ringer for OCZ's Vertex 3 - at least at the 120GB capacity. The two come with comparable warranties which brings the decision down to pricing, where OCZ currently has a $20 advantage.
That's about as open and shut as you can get. My preference is still 240GB for anything SF-2200 based given the sizable increase in performance, but that added performance and capacity does come at a high price. Speaking of which, OCZ's retail 240GB Vertex 3 is next on my hit list...
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altermaan - Thursday, May 5, 2011 - link
nice review though I'll most likely buy either the vertex 3 120GB max iops or the crucial m4 128GB. speaking of which: are there any plans of reviewing those two drives in the near future? I (and I think I'm might not be the only one) am desperately waiting for this as I don't wanna spend $300 for the wrong drive.greets
A
Nicolas Pillot - Thursday, May 5, 2011 - link
I see from the graphs, that- sequential read are faster than sequencial write, which seems ok
- random write are faster than random read, which seems illogical
That's the case for each and every ssd drive (well as far as i have checked)
Could somebody please explain this to me ?
Nihility - Thursday, May 5, 2011 - link
I'm not promising that this is the 100% correct reason, however it's possible that the random writes are being made to the cache (SSD's RAM) so that's quicker. While the reads have to be made from the actual flash storage.andymcca - Thursday, May 5, 2011 - link
Caching is another possible explanation, but if you run a test for any length of time (and I'm guessing the reviewers here do) logic dictates that your buffer will fill up if input rate > output rate.7Enigma - Thursday, May 5, 2011 - link
Makes sense to me. Writing to the drive only requires knowing where to put the data (ie is this block of space free or not). It's basically a limitation of how fast the cpu can deliver write requests to the SSD (so only 2 variables essentially).Random read on the other hand has an added variable of first FINDING the data on the SSD after the read request is made by the CPU. The latency of finding that data (as compared to writing in a free block) is where the performance difference occurs. This is why mechanical drives are so much slower than SSD's, but there still is an overhead on the "finding" part.
andymcca - Thursday, May 5, 2011 - link
Writes on SSDs are to wherever the drive wants to put them (not to a pre-defined physical location). Reads have to come from a pre-defined location, since that is where the data was already put. Basically, SSDs have to hunt for your read data, but put your write data somewhere convenient.JasonInofuentes - Thursday, May 5, 2011 - link
Could the power differences be a result of binning? Could be part of the perk of being Sandforce's favorite client.Thanks.
Jason
andymcca - Thursday, May 5, 2011 - link
My guess is that it has to do more with the memory and less with the controller, but IANAexpertaraczynski - Thursday, May 5, 2011 - link
I don't mean this as a stupid question (apologies if it is) but why not include a traditional platter driver in the ATStorageBench2011? Sometimes comparing apples to apples doesn't have the impact as when you also throw in an orange into the mix to help visualize what you're seeing.average MB/s of 100-200 on a certain bench doesn't mean much to me personally when i don't know how it compares to a traditional drive.
MilwaukeeMike - Thursday, May 5, 2011 - link
I agree. I like the Velociraptor included on some graphs because I own one, and know what the comparison is. These charts help us realize which SSD might suit our purposes best, but the question many of us are really wondering is 'should I upgrade to one at all?'The easy answer is 'yes', but having MS Word open in 1 second instead of 2 doesn't matter to me. Having my games load in 5 seconds instead of 25 does. But without an old school drive on the benchmark table we can't quantify SSD to HDD.
Review is great for SSD to SSD, don't get me wrong :)