On Fri, 2005-12-23 at 10:24 -0600, Mike McCarty wrote: > Umm, I believe the argument is not that it defrags itself, just that > the type of fragmentation it enjoys does not affect performance. Some > sort of fertilizer[*], if you ask me. > > ...[snip]... > > The ext3 file system is so much superior to other file systems, > that it runs as slowly as a fully fragmented disc ALL the time, > even when everything is fully contiguous. It's equally slow. I suppose there could be some truth in that. If it was equally slow, you wouldn't notice the difference. ;-) And if you were comparing it to an OS that was really really bad with fragmented drives... Since hard drives act in a non-linear fashion (data scattered about the drive, where the drive always has to seek around the hardware), unlike a tape (where data access has to work in a sequential manner for physical reasons), and modern hard drives are quite nippy, it may well be that you don't notice a small bit of hunting around. Looking around at various explanations, some reasons why you might not *usually* notice fragmentation seem quite straight forward: e.g. "The ext2 and ext3 file systems most often used on Linux systems also attempt to keep fragmentation at a minimum. These file systems keep all blocks in a file close together. How they do this is by preallocating disk data blocks to regular files before they are actually used. Because of this, when a file increases in size, several adjacent blocks are already reserved, reducing file fragmentation. It is, therefore, seldom necessary to analyze the amount of fragmentation on a Linux system, never mind actually run a defragment command. An exception exists for files that are constantly appended to as the reserved blocks will only last so long." Snipped from <http://www.itworld.com/Comp/3380/nls_unixfrag040929/> -- Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists.
