[jlopz]

Hello
I have the same problem after clone a 840 EVO (128MB) to a M500 (240MB). First I clone the drive (using Reflect), after that I increased the partition from 128 to 240 (using W7).

Tested with HD TUNE and HDTACH, performance is low just in the original data (about the half of the new disk) and normal in the other half. My system is a P55 3 GB SATA. The M500 is brand new, only 8 hours of use. 840 EVO is 1 year old (with the performance restoration passed 2 month ago as fas as I remember).

 

[jlopz]

Same test with 8 MB:

 

[jlopz]

And other test, this seen to be ok. I think that is the same problema that:
http://www.overclock.net/t/1518996/crucial-m500-poor-performance-similar-symptoms-to-840-evo/10#post_23528533

Any ideas of why?

 

[jlopz]

well. i think that it is better to close the question. Problem seems to be related to how HD Tune or HDtach works in SDD. In the crucial forum I have read the following:
"HD Tune is a HardDiskUtility and not suitable for Flash Memory, as it just reads LBAs without knowing if there is any date written to. If not, there is no Flash Adress mapped to the LBA and the controller does not read aynthnig for the NAND but just returns Zeros. See here: http://www.behardware.com/articles/860-4/ssd-2012-roundup-sixteen-120-and-128-gb-sata-6g-ssds.html
Another thinng is, that HD Tune with standard settings only reads 64kB every 8MB, that is why most SSDs have rather slow Read Rates with HD Tune, as 64k is just not enough to reach full seq. transfer rates. Uss CrystalDiskMark oder AS-SSD with SSD, as this benchmarks first write data to the drive and read them back later."