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 pro-actively erases these blocks and adds them to the free block pool.
To test the Ultra II's TRIM and garbage collection functions, 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 30 minutes. Looking at the screenshot below, you can see that the Ultra II's average read and write speeds dropped to 359.7 MB/s and 25.0 MB/s, respectively.
SanDisk Ultra II SSD - Dirty
To see how well the Ultra II could recover, I let the computer sit for about an hour and then reran the test. The drive's average read speed jumped back up to 434.7 MB/s. However, its write speed lagged a bit behind, averaging out at 217.7 MB/s.
SanDisk Ultra II SSD - After Trim
Lastly, I used SanDisk's SSD Dashboard utility to perform a secure erase on the Ultra II. With the drive wiped clean, its write speed jumped back up to 396.5 MB/s.
SanDisk Ultra II SSD - Secure Erase
Final Thoughts:
SanDisk's Ultra II SSD is a great choice for the consumer looking for an easy and affordable way to improve the performance of their existing desktop or notebook PC. The drive is based on TLC NAND flash technology and, depending on the capacity, is powered by either a Marvell 88SS9190 or 88SS9189 controller. The Ultra II also comes equipped with SanDisk's nCache 2.0 technology which utilizes a two-tiered caching architecture to optimize drive speed and endurance. In our sequential read and write tests, the Ultra II was able to read at speeds as high as 551 MB/s and write at speeds in excess of 474 MB/s. It also performed relatively well when doing random reads, but lagged behind the other drives in our random write tests, producing only 46,000 IOPS at low queue depths.
I do need to point out that SanDisk's nCache 2.0 technology does have its limitations. With its tiered caching architecture and On Chip Copy feature, nCache 2.0 does a great job of maintaining peak performance under normal workloads, but, once you make the transition from SLC to TLC NAND, the Ultra II's write speed drop considerably. If you use your computer primarily for web browsing, email or to play the occasional game, its unlikely that you will ever run into this situation. However, if you have a heavier workload and are doing something like video editing, which writes large amounts of data, you may want to consider other drives like the Samsung 840 EVO and Crucial MX100.
The SanDisk Ultra II is available now in 120GB, 240GB, 480GB and 960G capacities. Prices on Amazon.com and Pricegrabber currently range from $70 up to $400, with the 240GB version reviewed here going for about $110.
Highs:
- Available in 120GB, 240GB, 480GB and 960GB capacities
- Marvell 88SS9189 or 88SS9190 controller
- nCache 2.0 technology
- Excellent sequential read and write speeds under most conditions
- Good random read performance
- Performs equally well with compressible and incompressible data
- SATA 6Gb/s interface
- Large DRAM cache
- Supports TRIM, garbage collection and wear leveling
- Ultra-slim form factor
- Works with SanDisk's SSD Dashboard software
- 3 year warranty
Lows:
- Mediocre random write performance
- Does not support hardware based encryption
- Does not support DEVSLP
