On Sep 13, 2010, at 5:14 AM, 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.
Possible, yes. Probable, no. Consider that a file system is allocating space for multiple, concurrent file writers. > Also regardless of raid, it's possible to have contiguous or fragmented > files. The same concept applies to multiple disks. RAID works against the efforts to gain performance by contiguous access because the access becomes non-contiguous. -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
