Does RSYNC work over NFS?

[tim.conway at philips.com]

Actually, there is a possible exception to that.  Certainly, in my situation, I always use -W.  Ours is mostly new files or deletions... rarely partial modifications of large single files.
consider, however, a slow pipe between systems, one or more mounting filesystems via nfs over a fast connection.
the lan connection to the nfs is negligible versus the rsync connection from server to server.
We're on one side of  that threshold here, with a switched 1000bT connection from our servers to our Network Appliances filers and T1 from server-to-server (1044kbps).  Of course, we use slower-performing attached storage for our
organization-wide-duplicated filesystems, so there's no question in our case... it's -W... especially when we duplicate to our local redundant fileservers.
However, if we were using our netapps for our purpose, -W would slow us in some situations.

Tim Conway
tim.conway at philips.com
303.682.4917
Philips Semiconductor - Longmont TC
1880 Industrial Circle, Suite D
Longmont, CO 80501
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"There are some who call me.... Tim?"





David Bolen <db3l at fitlinxx.com>@lists.samba.org on 09/25/2001 05:08:58 PM

Sent by:  rsync-admin at lists.samba.org


To:     rsync at lists.samba.org
cc:      (bcc: Tim Conway/LMT/SC/PHILIPS)
Subject:  RE: Does RSYNC work over NFS?
Classification:



tim.conway at philips.com [tim.conway at philips.com] writes:

> yes, but I recommend you add the -W option, unless it's likely that
> you have a lot data changing within the files and a slow pipe.

I wouldn't even put any caveat on it.  Since rsync is going to have to
read the entire file anyway just to compute the block checksums
necessary for its algorithm, you're assured that the entire file will
flow across the NFS link no matter how much changed.  So it really
only makes sense to use -W and just copy the whole thing in the first
place.

To be honest, the only thing rsync offers over a straight copy over
NFS is the recursive comparison of timestamp/size to determine files
to copy.  That might still be worth it, but you're definitely not
going to get any benefit in terms of any delta computation.

-- David

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