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Hi,

Some days ago I read an interesting article about SSD performance degradation on Anandtech, and I kinda felt that this was happening to me also. I don’t own an SSD yet but I encountered flash performance degradation on my 8Gb Flash Voyager stick. Now I won’t go into the details about why flash performance degradation because the article above is more explanatory than I could make it. Suffice to say that I wanted to see if I can bring my stick back to life.

What was wrong with my voyager is that in the last weeks the write performance was poor. Whereas normally I could write at around 9MB/sec now I could only do it only at around 2-3MB/sec. From the article I understood that this was because even if the OS was reporting enough free space on the drive, all the space was already holding data and in order to write over it the flash needed to get the invalid data, write it to cache, delete the old location and then overwrite it with the new data. If one could delete everything from the location, subsequent writes would be just writes with no additional steps to execute, thus faster write speeds. This meant that I would need to do a format of the stick. But before that I had to do some tests to see performance before and after.

Let us see the scenario. Initially we have a full of data drive, even though the OS reported 7GB free out of 8Gb. I downloaded ATTO Disk Benchmark (I would have used HDTach but it does not work on my Windows7), and I ran a test of read/write for up to 256MB chunks. I stopped it when getting to 8Mb chunks as I saw no significant performance change going from 64K to 8Mb. You can see below the results:

Then I did a full format on the disk. Same FAT32 with 4096Kb allocation. The results on the write performance are in places 2.5 times greater. The read speed was the same. See below:

Of course format is not an action that you want to do often, as flash cells have a limited lifespan. But when a 2.5 times write performance penalty occurs I would certainly do it, especially when you really need this and paid top dollar for your flash (read Flash Voyager GT and the likes).

My testing machine specs (just so no one comes with remarks like “the test was bottlenecked somewhere”): Intel Core2Duo 6550 2.6Ghz, 4Gb DDR2 Corsair, Gigabyte P35 motherboard and a 500Gb Caviar Black HDD.

Cheers

This entry was posted on Saturday, March 21st, 2009 at 10:23 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.