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On Thu, 29 Apr 2010, tom wrote:
SubBASS wrote:I,m a bit out of date on the technical stuff but it used to be that each bit of storage was re-usable a certain number of times. This meant that you could only do so many read/write operations before failures cropped up. Nowadays they have slightly smarter algorithms that move things around the ssd to try an even out wear however I think things like swap can still cause problems so you can still wipe one out a lot faster than 5 years.On Wed, 2010-04-28 at 23:28 +0100, Julian Hall wrote:Something I've wondered about for a while, but keep forgetting to ask.As I understand it, SSD lifespan is measured in numbers of r/w cycles, as discussed at http://hothardware.com/News/Two-Methods-for-Measuring-SSD-Lifespans/ With that in mind is it such a great idea to put an OS on an SSD as it will be almost constantly engaged in readign and writing, far more so I would have thought than a data drive - depending on the user of course.The intel I got is something like 1,200,000 hours mtbf I think I read, which my calculator tells me is 136 years.... I somehow doubt that is its average lifespan in real applications, if it goes 5years though it will do. The upside of an SSD is when it does fail from exhausted read/writes, it merely becomes read only afaik, no catastrophic data loss, which I have to say I am in favour of :]
So don't have swap... :)Actually, from observations it's applications like firefox, etc. that are becoming "smarter" and desperately trying to keep "state" between crashes that I have a suspicion might be worse... I've noticed that firefox uses sqlite3 a lot now - that will imply disk flushes often to make sure the database is on-disk, and will force page erase & re-writes by the SSD device.
Other apps I've noticed: The user-data on my N900 is all held in sqlite3 databases, so the underlying flash/ssd in there is going to be written frequently too - I imagine other phones do something similar, but maybe they have written into their OS some other form of wear leveling.
There is a flash driver for Linux that can do this too, but I've forgotten what it's called - I did look at it years ago, but decided it was easier to let the hardware manage it.
Gordon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html