Flash SSD Performance Degradation.. Explained!
A great article on anandtech spends a moment to explain the performance degradation of NAND flash SSD based drives:
“As far as the OS is concerned we needed to write 12KB of data and it got written. Our SSD controller knows what really transpired however. In order to write that 12KB of data we had to first read 12KB then write an entire block, or 20KB.
Our SSD is quite slow, it can only write at 1KB/s and read at 2KB/s. Writing 12KB should have taken 12 seconds but since we had to read 12KB and then write 20KB the whole operation now took 26 seconds.
To the end user it would look like our write speed dropped from 1KB/s to 0.46KB/s, since it took us 26 seconds to write 12KB. ” [source: anandtech]
If only more engineers could do such succinct and clear presentations, we might not have the dilbert image problem. On the other hand, then we might not be engineers.