More thoughts on SSDs - Life Expectancy
Just been over to Anandtech where Anand has a review of the latest Sandforce controllers in a beta of OCXs Vertex 3 drive.
http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-the-first-sf2500-ssd
EDIT: That was in fact the Enterprise version, here's the skinny on the consumer SKU and what the differences are. http://www.anandtech.com/show/4186/ocz-vertex-3-preview-the-first-client-focused-sf2200
He clears up the issue of SSD life span very well. To sum up the original spec for 50nm Nand was 10,000 erases, 35nm is generally around 5,000 and the new 25nm is around 3,000, this doesn't sound like a lot of lifespan but once you understand how these things work yu will appreciate it is quite a long time.
SSDs only wear when individual cells are wiped so basically the controller tries do everything it can not to do that, however the wipe cycle takes time so there is a balancing act between wiping early to avoid slow downs and leaving it to the last possible minute to avoid wear.
To work out how long a drive will last you need to know two things, how big it is and how much data is written to it every day.
A heavy user will write as much as 10GB a day though I doubt I would write more tha 2 or 3GB but for the purposes of this illustration I will assume a nice round 5GB.
My C300 is 64GB in capacity so at 5 GB a day it would take 13 days or there abouts to fill the drive. This would represent one delete cycle. now I have the minmum 5,000 cycle Nand so my drive will last about 13 x 5000 days or 65,000 days which is around 178 years. It's shame the warranty doesn't last that long. A 128GB drive will last twice as long as it will take 2 twice as long to fill it. Double the write rate and you half the life expectancy but that's still around 90 years for the 64GB drive.
The controllers should be clever enough to make sure all the Nand cells wear at the same rate.
In an enterprise storage system you would need to look at how much data is actually written to the storage to see what your life expectancy is, heavy transactional databases may kill an array of SSDs in much less time, though would benefit hugely from the speed of the drives, datawarehouses with a lot of reads but only a few write could last forever if you can afford the capacity.
For those of you who like to know these things my Crucial C300 64GB has a Windows 7 performance index of 7.7, higher capacity droves should be larger.
http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-the-first-sf2500-ssd
EDIT: That was in fact the Enterprise version, here's the skinny on the consumer SKU and what the differences are. http://www.anandtech.com/show/4186/ocz-vertex-3-preview-the-first-client-focused-sf2200
He clears up the issue of SSD life span very well. To sum up the original spec for 50nm Nand was 10,000 erases, 35nm is generally around 5,000 and the new 25nm is around 3,000, this doesn't sound like a lot of lifespan but once you understand how these things work yu will appreciate it is quite a long time.
SSDs only wear when individual cells are wiped so basically the controller tries do everything it can not to do that, however the wipe cycle takes time so there is a balancing act between wiping early to avoid slow downs and leaving it to the last possible minute to avoid wear.
To work out how long a drive will last you need to know two things, how big it is and how much data is written to it every day.
A heavy user will write as much as 10GB a day though I doubt I would write more tha 2 or 3GB but for the purposes of this illustration I will assume a nice round 5GB.
My C300 is 64GB in capacity so at 5 GB a day it would take 13 days or there abouts to fill the drive. This would represent one delete cycle. now I have the minmum 5,000 cycle Nand so my drive will last about 13 x 5000 days or 65,000 days which is around 178 years. It's shame the warranty doesn't last that long. A 128GB drive will last twice as long as it will take 2 twice as long to fill it. Double the write rate and you half the life expectancy but that's still around 90 years for the 64GB drive.
The controllers should be clever enough to make sure all the Nand cells wear at the same rate.
In an enterprise storage system you would need to look at how much data is actually written to the storage to see what your life expectancy is, heavy transactional databases may kill an array of SSDs in much less time, though would benefit hugely from the speed of the drives, datawarehouses with a lot of reads but only a few write could last forever if you can afford the capacity.
For those of you who like to know these things my Crucial C300 64GB has a Windows 7 performance index of 7.7, higher capacity droves should be larger.
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