[Samba] extending files slow on FAT filesystems

[Jeremy Allison]

On Thu, Aug 24, 2006 at 05:51:45PM +0200, Mattias Rönnblom wrote:
> Hi,
> 
> I'm running Samba 3.0.23a on Linux. One of my share is a USB disk with
> a FAT32 filesystem.
> 
> When copying large files from my Windows XP machine to this share,
> smbd seem to "reserve" (by using ftruncate()) the space needed on the
> USB disk before actually doing any copying. This ftruncate() operation
> takes quite a while when the file is large. It may even cause the
> client to time out.
> 
> If I reformat the disk with ext2, ftruncate() runs fast.
> 
> Is there some way of turning off this "pre-allocation" behaviour? I've
> consulted smb.conf(5), but I've been unable to find anything of use.
> 
> Would you consider this a problem in Samba or in the VFAT filesystem
> driver?

VFAT system driver. Samba is just calling ftruncate in this 
case. You can control this behaviour by setting "strict allocate = no".

Jeremy.