TRIM Performance:
While SSD's 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 fix 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 SU900'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. This had little impact on the SU900's read speed. However, its average writing speed dropped to a mere 20.9 MB/s.
ADATA Ultimate SU900 - Dirty
To see how well the SU900 could recover, I let the computer sit for about 30 minutes and then reran the test. The drive's average read speed climbed up to 458.9 MB/s. However, its write speed lagged behind, averaging out at only 151.6 MB/s.
ADATA Ultimate SU900 - After TRIM
Lastly, I used Parted Magic to perform a secure erase on the SU900. With the drive wiped clean, it had average read and write speeds of 466.0 MB/s and 392.7 MB/s, respectively.
ADATA Ultimate SU900 - Secure Erased
Final Thoughts:
The ADATA Ultimate SU900 is a great choice for the consumer or enthusiast looking to improve the performance of their existing desktop or notebook computer. The drive combines Silicon Motion's SM2258 controller with 3D MLC NAND to deliver good performance, enhanced features and a high level of endurance at a price that isn't much more than some TLC NAND-based SSDs. In our sequential read and write tests, the 256GB version of the SU900 was able to read at speeds as high as 563 MB/s and write at speeds in excess of 505 MB/s. It also did surprisingly well in our random write tests, producing more than 67,000 IOPS at low queue depths.
Of course, fast read and write speeds aren't the only things the Ulimate SU900 has to offer. In addition to a large DRAM cache buffer, the drive uses an intelligent SLC caching algorithm to boost read and write performance. The SU900 also features advanced LDPC error correction, data shaping, wear leveling and a RAID Engine to ensure data integrity and extend the lifespan of the SSD. To top it all off, the drive is backed by a 5 year warranty.
The Ultimate SU900 is available now in 256GB, 512GB and 1TB capacities. Prices on Amazon.com start at $108 for the 256GB version and go up to $390 for the 1TB drive. The 2TB model has not shipped at the time of this review and there is no clear indication as to when it will be available.
Highs:
- Available in 256GB, 512GB, 1TB and 2TB capacities
- Silicon Motion SM2258 controller
- 3D MLC NAND
- Good sequential and random read and write performance
- Huge SLC cache
- RAID Engine, Data Shaping and LDPC ECC technologies
- Ultra-slim form factor
- Includes mounting spacer for 9.5mm applications
- DEVSLP power mode
- SSD Toolbox and Migration Utility
- Reasonably priced for MLC NAND-based drive
- 5 year warranty
Lows:
- Write speed drops considerably when SLC cache is full
- Does not support hardware based encryption
