On 12/26/2010 02:08 PM, Jeff Garzik wrote: > On 12/26/2010 01:53 PM, nodata wrote: >> On 26/12/10 18:42, drago01 wrote: >>> On Sun, Dec 26, 2010 at 6:34 PM, Ray Strode<halfline@xxxxxxxxx> wrote: >>>> Hi, >>>> >>>> On Sun, Dec 26, 2010 at 10:32 AM, drago01<drago01@xxxxxxxxx> wrote: >>>>> You don't want to use LVM (and you should mount the fs with the >>>>> discard option for trim to work). >>>> At plumbers it came out during the filesystem talk that the discard >>>> option is a really bad idea. It apparently has performance and >>>> reliabilty problems. Apparently, you're just supposed to run a >>>> command manually (that I don't remember of hand) when your disk starts >>>> to fill up. >>> Yeah this depends on the drive though (on my Samsung drive it does not >>> seem to have a noticeable performance hit). >>> >>> The tool that can be run from time to time is the "wiper.sh" script >>> found in the hdparm tarball. >> Manually running a script "from time to time"? Can't we run this >> automatically instead? Why doesn't the drive do this? > The drive must first be informed of what sectors are empty or occupied, > because from the TRADITIONAL hard drive's perspective, all sectors are > always occupied by data. TRIM/DISCARD command has changed this, by > creating a method of telling the hard drive what sectors are empty. > > Only the filesystem knows which sectors are empty or occupied, so your > choice is > > (a) inform drive of empty sectors, each time a file is deleted > > (b) periodically (once a day or week or month, etc.), inform drive of > empty sectors that have appeared since last check. > > Option (a) apparently slows down file deletion noticeably, and > potentially "erases" sectors that will be immediately re-filled with > useful data (== extra, unnecessary work). > > That leaves option (b). > > Jeff > Various drives perform better or worse with file system, fine grained discard support so not all will see a performance hit. Ric -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
