On Mon, September 13, 2010 07:14, Edward Ned Harvey wrote: >> From: Richard Elling [mailto:rich...@nexenta.com] >> >> This operational definition of "fragmentation" comes from the single- >> user, >> single-tasking world (PeeCees). In that world, only one thread writes >> files >> from one application at one time. In those cases, there is a reasonable >> expectation that a single file's blocks might be contiguous on a single >> disk. >> That isn't the world we live in, where have RAID, multi-user, or multi- >> threaded >> environments. > > I don't know what you're saying, but I'm quite sure I disagree with it. > > Regardless of multithreading, multiprocessing, it's absolutely possible to > have contiguous files, and/or file fragmentation. That's not a > characteristic which depends on the threading model. > > Also regardless of raid, it's possible to have contiguous or fragmented > files. The same concept applies to multiple disks.
The attitude that it *matters* seems to me to have developed, and be relevant only to, single-user computers. Regardless of whether a file is contiguous or not, by the time you read the next chunk of it, in the multi-user world some other user is going to have moved the access arm of that drive. Hence, it doesn't matter if the file is contiguous or not. -- David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
