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 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 950 PRO'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 950 PRO's read speed. However, its average writing speed dropped to a mere 87.3 MB/s.
Samsung 950 PRO - Dirty
I let the computer sit for about an hour and a half and then reran the test. Looking at the screenshot below, you can see that the 950 PRO's average write speed had increased to a 95.0 MB/s. Needless to say, this was not the result I expected, especially when you consider how well the 850 PRO and EVO did in this test.
Samsung 950 PRO - After TRIM
With this in mind, I went back and reran the test using AS SSD instead of HD Tach. AS SSD isn't as low level as HD Tach nor does it produce a nice looking graph. However, it does let us test a drive's read and write speeds without having to delete the volume. I used Iometer to fill 80% of the drive and then ran a random write test for 30 minutes. Once again, this had very little effect on the drive's read speed. However, its sequential write speed dropped to 393.45 MB/s
Samsung 950 PRO - Dirty
I let the computer sit for about 30 minutes and then reran the test. The 950 PRO wasn't able to reach the factory fresh performance shown in our earlier tests. However, its average write speed climbed up to 1413.21 MB/s.
Samsung 950 PRO - After TRIM
Lastly, I used Samsung's SSD Magician software tpo perform a secure erase on the 950 PRO. With the drive wiped clean, it had average read and write speeds of 2174.87 MB/s and 1446.87 MB/s, respectively.
Samsung 950 PRO - Secure Erase
