On Sat, Sep 29, 2012 at 11:15:45PM +0200, Bastian Blank wrote: > > If you have 5000 erase cycles, it will run for 13 years if you overwrite > it once per day. Do you really expect this device to work until this?
Why not, my computer upgrade cycles are about 6-8 years and the computer won't be idling all the time - especially considering modern desktop environments running whole database engines to store config/meta data. Is writing of 160GB/day realistic? Hopefuly not, but see my apt measurements below. There is also something called SSD write amplification - the erase blocks on the device are often larger than your normal filesystem blocks, which might lead to up to 10x data actually writen to SSD, i.e. down to 1.3years of overwrites in the extreme case. > > iostat (part of sysstat) revealed, that simple apt-get update command > > generated about 250MB of writes! > > How does it reveal this? Running iostat -dm -p sda before and after apt-get, looking at the MB_wrtn column. Immediately after boot to xmonad: Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn sda 81,24 1,96 0,12 175 10 sda1 3,38 0,01 0,00 1 0 sda2 64,64 1,89 0,12 170 10 sda3 1,78 0,01 0,00 0 0 sda4 0,02 0,00 0,00 0 0 sda5 1,82 0,01 0,00 0 0 sda6 3,65 0,02 0,00 1 0 sda7 5,56 0,02 0,00 1 0 After running apt-get update after about a week (relevant device only, focus on the last column): Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn sda2 42,66 0,75 4,32 246 1413 so just updating the package info wrote 1.4GB of data (disabling pdiff might help as you suggested) After running apt-get upgrade (expected APT DL size: 87.2MB): Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn sda2 56,43 0,36 2,69 317 2376 so installing 90 MB of packages produced about 900 MB of writes Running apt-get update again (there is nothing to update right now), about 40 MB of data are written in each subsequent run. > Disable pdiffs, mount /var/cache/apt as tmpfs, so at least the packages > are not written again. Good call, thanks Frank -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/CAPds5_KFZ+oHC5Z5iEErCPycP-yOEMq17FGuFQ=tmytwxr3...@mail.gmail.com