rsycnc copies all files

[Jason Haar]

On Thu, Jun 17, 2004 at 04:17:06PM -0600, Tim Conway wrote:
> I don't know the nature of your filesystems, but I have a guess... on at 
> least one end is a network filesystem - NFS, SMB, NCP, AFS, something like 
> that.  rsync has the "-W", or "--whole-file" option, which tells it that 
> there's no point in trying to read the file for changes - if it needs 
> transferring, just send the whole thing, because the LAN overhead will 
> waste the savings in WAN.  Last I heard, -W was going to be forced if 
> either end was a network filesystem.

Owch - is that really a good idea?

We use rsync to replicate data between Windows servers over our WAN - but
via Linux "rsync servers". They smbfs mount the Windows servers, and rsync
Linux-to-Linux. We found the Linux ipstack outperformed Win2K on our WAN,
and rsync should be "better" on Unix as a pure, written-for-Unix product.

Our Linux and Windows servers are on 100Mb Ethernet, and our WAN runs
between 0.5-1.0Mbs max. So *I'd have thought* the extra latency slowdown
with rsync having to do SMB i/o would still be negliable compared with the
gain in doing partial data transfers over the (much slower) WAN.

Does the "reading" of files in "rsync -a" mode really have that massive an
impact for rsync-over-WAN?

BTW: what would be the best way of running rsync for such an environment? We
currently just do "rsync -az src_dir/ remote::xxx/dst_dir"

-- 
Cheers

Jason Haar
Information Security Manager, Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417
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