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On Thu, 4 Feb 2010, Simon Waters wrote:
Rhia Knowles wrote:I think this is where SSDs come in. Removing the moving parts to remove one reason for failure (heads impacting on platters) and the energy costs for those on the move, but they are increasing the capacity on those too.I always thought the drive for SSD was to do away with seek time.
My thoughts too, but I'm sure I read something recently about some of them having real performance issues in that department.
My own experiences with an addmittedly small device in my AAO is that writes will completely stall the device. It's almost as bad as being back in the bad old PIO/non DMA days.
So I think the manufacturers still have a lot of work to do on them.
The issue of limited writes for flash is I think solvable in software. We've reached the point where flash disks using a sensible levelling strategy can live as long as the PC they are in is likely to.
There are drivers for doing this in Linux, but I think it's much better to push it to the device - and hope that the makers have a better idea of how to do it than some random program - the issue then in that if the device has to autonomously do a read/write operation to move some data is that it can do it under it's own battery/super cap power than rely on the host, should the host "go away" for whatever reason...
All sorts of buffering strategies are now being trialled - including putting a spinny drive next to it! I wonder how long it'll be before you buy a device "optimised for streatming", or "optimised for database use", or "optimised for laptop use", etc.
I've always wondered what makes them so expensive when compared to (e.g.) compact Flash drives - these now have write wear levelling in them too, but I guess they lack the clever buffering, etc. I use CF (and IDE Flash disks) in my embedded stuff, and I've always been paranoid about the number of writes to them though. The new CF drives I use are faster than the SSD in my AAO. (And there is an aftermarket mod for the AAO to fit a CF drive into it!!!)
Now I've just seen a load of disk errors from one of my desktop drives. That means 2 out of three of the hard disks in my desktop machine are failing this week. And this one won't be in warranty......
good luck!
Argh.... I probably need a new computer but it'll have to be another disk drive instead. Fortunately it is part of a RAID mirror so hopefully it'll limp along another few days and won't eat my data.
Stick a Drobo on 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