Re: defrag and error checking

Kurtis Peterson wrote:
> Error checking comes in the form of fsck but there is no defrag as linux
> (and more specifically the ext 2/3 file system) is a "neater" way to
> write files to the drive and theoretically doesn't need to be
> defragged. Windows and the Fat or NTFS file systems can be very messy.
> They start writing new files in the first availible free space

This is not (strictly) true.

All file systems attempt to allocate contiguous blocks. Due to the
nature of how FAT works, lack of contiguous blocks = lots of HD syncs
since it's just a linked-list of blocks.

NTFS and EXT[23] use trees which allow for minimal seeking. There is
little/minimal overhead from breaking up files (if need be). NTFS and
EXT[23] should not require defragmentation if you keep enough free
space. As files are read/written, the FS logic will reallocate space to
reduce fragments as possible. In this regard, NTFS is much better than FAT.

> regardless of whether that free space is big enough to handle the file
> or not. After time this requires you to Defragment the drive by moving
> files around so they are contiguous on the drive. Linux doesn't work
> this way and has background daemons which are constantly optimizing the
> drive with spare CPU cycles so you really don't need to. Give fsck a

You have to run e2fsdefrag or the like if you want that -- it's not a
daemon, but part of the FS layer of the kernel.

> try and if that doesn't work it probably means there is another issue
> and it's not your file system.

I would suspect hardware issues. Ubuntu isn't Slackware-stable, but I'd
still go with my gut of marginal RAM/CPU over a software issue on the
Linux side if you are experiencing true random/unexplained behaviour.
If you're experiencing easy-to-repeat behaviour, that's a software bug
somewhere. Windows drivers are usually so poorly written that this
leads to lots of troubles (ATI => 0x000 STOP stuff, etc).

Defragmentation will have no effect on a computer in terms of stability,
only in terms of IO throughput, and then only on poorly designed (FAT 16
or 32) file systems.
Received on Thu Aug 23 16:05:34 2007