OWC Mercury Extreme Pro 120GB Solid State Drive Review

Firmware, Trim & Self Maintenance

As you can see the firmware which comes preloaded on the Mercury is labelled as "310A13F0"; and as such this is the latest “mass production” firmware and is commonly referred to as simply “310” . What this means it has all the tweaks and bug fixes that go along with later firmware revisions but also has the same performance limiting issues we mentioned in the past. As discussed in a earlier reviews, SandForce hobbled the small file IO/s performance of all but the Vertex 2 starting with firmware 305.

What this all this means is that in theory this drive’s competition is more along the lines of the Agility 2 Extended and not the Vertex 2 Extended. However, since this is the only drive we have tested with the newer 310 firmware it will be interesting to see if SandForce eased up on their choke hold and allowed non OCZ customers a bit of breathing room on the performance end of things.

This is not the first time we have seen this firmware revision as OCZ has had their own firmware 1.1 out for a little while now. Since we have already retested the OCZ (expect to see some new numbers in the charts!) and know what the potential of this firmware is, any variation will be readily apparent.

For anyone who has a 100GB OWC - or other 100GB SandForce drive for that matter - please don’t get your hopes up. Firmware 310 - like 309 before it - will not make your 100GB drive into a 120GB product (or 50 into a 60, etc etc). It simply allows both “standard” and “extended” drives the ability to run the same firmware, making for less confusion and less chance of bricking your drive by trying to flash an “incorrect” firmware. SandForce literally just rolled both slightly different firmwares into ONE package.


For anyone interested in whether or not the upcoming OCZ Toolbox (0.6 beta) works on the Mercury Extreme Pro the answer is: yes it works. One of the nicest features we have found with this program - besides it ability to remove the issue of SMART monitoring programs from reporting it as bad via a secure erase - is to see exactly how many free cells are left in reserve to replace dead ones.

One Note of Concern (And Some Really Technical Stuff)

In OCZ’s ToolBox, we have yet to see a drive with 100% replacement blocks showing “out of the box” but this drive is the very first one which showed a mere 98%. Worse still was the fact that by the end of testing it had sunk down to 88% with 2048 bad blocks replaced. We may be hard on these drives in testing but losing an additional 10% of reserved cells to usage (as new bad ones die an early death) is disquieting to say the least.

This is a direct result of the extended firmware scheme and with all things in life there is no free lunch. To get the “extra” 20GB of space you need to be willing to give up something and it appears the disconcerting down side is a severe curtailing of this drive’s potential lifespan. We say this as while you get in theory 10,000 writes cycles per cell not all cells are going to last that long. This is where the replacement blocks come in handy as they replace the bad ones seamlessly and usually before catastrophic failure and loss of data. Once you run of out replacement blocks, the drive’s lifespan starts decreasing exponentially.

Based on an admittedly small sample size it appears SandForce reduced the over-provisioning of replacement blocks by at least 300%. For example, an OCZ Vertex 2 100GB with 1728 bad blocks shows as 96% of its free cells still available for approximately 49152 (48 in binary) to 51200 (50 in binary) replacement blocks set aside. This assumes the “1728” number (1.6 in binary) would go as high as 2048 (2 in binary) before going down further in percentage. Whereas 2048 bad blocks for a total of 12% of the OWC’s over-provisioned blocks works out to be about 16384 (16 in binary) replacement blocks. We are not going to get into the issue of potential reduction of error correction / checksum tables that makes up RAISE as, unlike bad block replacement & allocation, it is conceivable that this data is now being written in amongst the 120GB of space.

To put this into perspective, 8GB of free cells just waiting to jump into action to replace early death cells is still pretty darn good for most consumer orientated solid state drives. It’s just not anywhere near as good as the number of cells the 100GB drives have in reserve.