Re: ReiserFS problems

[Mike Fedyk <mfedyk@matchmail.com>]

On Wed, Aug 06, 2003 at 09:36:23PM +0200, Rogier Wolff wrote:
> P.S. We also sometimes do: 
> 
> 	while (1)
> 	   seek to random position (in randomly chosen 1G file)
> 	   write 1k
> 
> we might benefit from a call that tells the filesystem:
> Pretend that this file WILL grow to 1Gb, but leave it sparse for
> now.
> 
> So, the block to allocate if we seek to 500Mb past the beginning of the
> file would be 500Mb further along the disk. That way the eventual image
> will be linear. But leaving the intermediate blocks unallocated will 
> allow us to  eventually use up that free space if we DO NOT end up
> writing that area. 

Ahh, but sparse files are not handled effeciently at all with reiserfs.  It
is fixed properly in reiser4 though.  There was a thread recently on this
issue on the reiserfs list within the last week about this.

If you use reiserfs, avoid large sparse files like the plague.