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This is encouraging although even tests on early drives showed that an 'average' drive should last far longer than people need them for - purely based on the nu

by joshvm 12y ago

This is encouraging although even tests on early drives showed that an 'average' drive should last far longer than people need them for - purely based on the number of allowed writes. 750TB? That's more data than my department, an imaging research group, have on our cluster... There are some more tests which are very hard to do because you need time and a large sample size, for instance what's the data retention time for a typical SSD? As far as I can tell, nobody really knows because you'd need to leave the drive off for probably more than a year - and as soon as you turn the drive on, presumably you refresh the charge that's leaked out? Most of the time this isn't a problem because almost everyone turns on their PC or laptop weekly/monthly if not daily.

sounds 12y ago
> as soon as you turn the drive on, presumably you refresh the charge No, bits lose their charge slowly but it doesn't matter whether the SSD is powered on or off. http://www.tomshardware.com/forum/256180-32-read-longevity http://www.tomshardware.com/forum/256180-32-read-longevity As a side note, the really interesting thing about this endurance test is that almost all the drives fail badly at the end of their life. Even though almost all the manufacturers specifically claim they "fail safe" into a read-only mode.
frozenport 12y ago
It's frequently assumed that breakdowns are geometric random variables and we can extrapolate the rate by testing many drives. For example, test 100 drives.and find when the first one breaks. The numbers in this test should be interpreted as an average with some drives breaking earlier. Now consider the failure rates for drives where the file is spread across multiple disks.
dzhiurgis 12y ago
If you don't have much RAM I suppose you'd hit these limits much faster as OS would swap a lot of data onto drive.
- alexbecker 12y ago
  If you're swapping regularly then you have more immediate computer needs than a fast hard drive.
  - vidarh 12y ago
    I actually wish I could turn swap off safely on my work computer, because I actually have enough RAM for normal situations. Swap may eventually be an old curiosity for most people, and a "niche thing" for others... When I start swapping, it's a sign some application is leaking memory and I'd rather it didn't get any and crashed instead of freezing the machine up for ages while trashing the drive. But as it turns out OS X behaves really badly if you try to take away its swap (last time I tried, the kernel memory usage slowly increased until it consumed almost all memory; I re-enabled flash and rebooted and it got back to normal. It's a bit annoying that we've become so dependent on a kludge to work around too little memory. (Brings me back to my Amiga days and the long, heated discussions about whether or not swap was a good idea in the first place)
    - dmm 12y ago
      One trick people in a similar situation on linux use is to make a small ram disk and then assign that as the swap. A little absurd but prevents the bad behavior.
      - darkr 12y ago
        It is indeed absurd, when swapping can be avoided entirely by setting kernel swappiness to 0: sysctl -w vm.swappiness=0 to make permanent, set vm.swappiness=0 in /etc/sysctl.conf Though for a desktop machine, disabling swap probably won't help improve performance
        dmm 12y ago
        That's true, but this was a special circumstance where disabling swap was creating very bad system behavior.

by joshvm 12y ago

sounds 12y ago

> as soon as you turn the drive on, presumably you refresh the charge No, bits lose their charge slowly but it doesn't matter whether the SSD is powered on or off. http://www.tomshardware.com/forum/256180-32-read-longevity http://www.tomshardware.com/forum/256180-32-read-longevity As a side note, the really interesting thing about this endurance test is that almost all the drives fail badly at the end of their life. Even though almost all the manufacturers specifically claim they "fail safe" into a read-only mode.

frozenport 12y ago

It's frequently assumed that breakdowns are geometric random variables and we can extrapolate the rate by testing many drives. For example, test 100 drives.and find when the first one breaks. The numbers in this test should be interpreted as an average with some drives breaking earlier. Now consider the failure rates for drives where the file is spread across multiple disks.

dzhiurgis 12y ago

If you don't have much RAM I suppose you'd hit these limits much faster as OS would swap a lot of data onto drive.

alexbecker 12y ago
If you're swapping regularly then you have more immediate computer needs than a fast hard drive.
- vidarh 12y ago
  I actually wish I could turn swap off safely on my work computer, because I actually have enough RAM for normal situations. Swap may eventually be an old curiosity for most people, and a "niche thing" for others... When I start swapping, it's a sign some application is leaking memory and I'd rather it didn't get any and crashed instead of freezing the machine up for ages while trashing the drive. But as it turns out OS X behaves really badly if you try to take away its swap (last time I tried, the kernel memory usage slowly increased until it consumed almost all memory; I re-enabled flash and rebooted and it got back to normal. It's a bit annoying that we've become so dependent on a kludge to work around too little memory. (Brings me back to my Amiga days and the long, heated discussions about whether or not swap was a good idea in the first place)
  - dmm 12y ago
    One trick people in a similar situation on linux use is to make a small ram disk and then assign that as the swap. A little absurd but prevents the bad behavior.
    - darkr 12y ago
      It is indeed absurd, when swapping can be avoided entirely by setting kernel swappiness to 0: sysctl -w vm.swappiness=0 to make permanent, set vm.swappiness=0 in /etc/sysctl.conf Though for a desktop machine, disabling swap probably won't help improve performance
      - dmm 12y ago
        That's true, but this was a special circumstance where disabling swap was creating very bad system behavior.