TRIM Performance:
While SSDs offer many benefits, there are some downsides to using flash memory. One of the biggest issues people run into is performance degradation. Over time, an SSD will run out of fresh blocks and will have to write over data the file system has marked as deleted. This procedure is very complicated and can slow an SSD's write speeds considerably.
To address this problem, most manufacturers have added TRIM support to their SSDs. The TRIM command allows an operating system, such as Windows 7, to tell an SSD which data blocks are no longer in use. Using this information, the drive proactively erases these blocks and adds them to the free block pool.
I should point out that the S70 ships with SandForce's 5.0.3 firmware. Earlier releases of the Series 5 firmware had problems with TRIM, which are fixed in this version.
To test the S70's TRIM function, I first put the drive in a "dirty" state. I used Iometer to fill the entire drive and then ran a random write test for 20 minutes. Looking at the screenshot below, you can see that the S70's average read and write speeds dropped to 153.6 MB/s and 216.2 MB/s, respectively.
Silicon Power S70 240GB - Dirty
To see how well the S70 could recover, I let the computer sit for a few hours and then reran the test. The drive's average read speed jumped back up to 318.6 MB/s. However, its write speed lagged a bit behind, averaging out at 272.4 MB/s.
Silicon Power S70 240GB - After Trim
Lastly, I used an older version of OCZ's Toolbox utility (yes, it works) to perform a secure erase on the S70. With the drive wiped clean, its average write speed jumped back up to 395.6 MB/s.
Silicon Power S70 240GB - Wiped
Final Thoughts:
While SandForce-based SSDs are a dime a dozen these days, those capable of fitting in an ultra-slim notebook are still few and far between. With the Slim S70, Silicon Power has addressed the needs of this rapidly growing market. Along with a slim and stylish enclosure, the S70 combines LSI's SandForce SF-2281 controller with Intel's 25nm synchronous NAND flash to deliver some impressive performance. In our sequential read and write tests, the drive was able to read at speeds as high as 557 MB/s and write at speeds in excess of 490 MB/s. It also performed very well in our random write tests, delivering more than 80,000 IOPS. As with other SandForce drives, the S70's performance did take a hit when reading and writing incompressible data. However, thanks to its synchronous NAND flash, its performance didn't suffer nearly as much as some other drives.
That being said, I do have a few issues with the S70. First and foremost, is the lack of firmware updates on Silicon-Power's website. I can only imagine that this is the company's way of preventing people from flashing their drive and potentially losing their data but anyone who has owned a SandForce-based SSD knows how important firmware updates can be. Silicon Power also needs to be clearer regarding the type of NAND flash used in their drives. In the case of the S70, the company makes reference to "Toggle/Synchronous" flash in its promotional materials and even lists it as a feature on the box. Like many, I took this to mean that the drive used Toggle-Mode NAND and was a bit surprised to find that wasn't the case.
The Slim S70 is currently listed on Amazon but is not yet in stock at the time of this review (Update: the 120GB and 480GB versions are now in stock). Prices currently range from $120 up to $433, with the 240GB version reviewed here listed at $210. These prices are a little higher than other SandForce-based SSDs. However, I'd expect them to come down to about where the Velox V70 is currently at once the S70 starts to ship.
Highs:
- Available in 60GB, 120GB, 240GB and 480GB capacities
- Slim 7mm form factor
- SandForce SF-2281 processor
- Excellent sequential read and write speeds
- SATA 6Gb/s interface
- Synchronous NAND flash
- Supports SMART, TRIM and Garbage Collection
- Equipped with DuraWrite and wear leveling
- Good looking and well constructed design
- 3 year warranty
Lows:
- Does not include a 2.5" to 3.5" adapter bracket
- Not as fast when writing incompressible data
- Hard to find in some markets
- Pricey
