1) Yes! 2.6.x especially helps with memory.
2) Not that I've seen, but I'd be really interested!
3) We've had great luck with (Open)AFS, though it's not for everyone, not even in our environment. =) (having to load a kernel module being #1 complaint). rsync allows us to accommodate those that don't wish to use AFS.

Here's what we're doing:

Roughly 10% (~1k hosts) of our install-base use rsync as an alternative to AFS (our system configuration and application store). About 250M is checked hourly, though as often as every 15 minutes for more time sensitive systems. We've tossed around the idea of using batch-mode, but it unfortunately doesn't fit our model - It's basically a huge buffet of data that the hosts pick and choose which trees to keep in sync.

What we've found is client initiated pulls scale much better than pushes from a central server. We have each host sleep for a random amount of time using the hostname as a seed (so it's the same from run to run) before initiating the rsync. This causes multiple rsyncs to be run on the server, but it can handle dozens of connections at a time without issue, especially after the switch to 2.6 versions of rsync.

We also have multiple servers from which the client can rsync from, but that is handled similarly to the timing: A host randomly picks a server from a list using hostname as the seed. The servers are monitored for load and new ones added appropriately. Our server to client ratio is close to 50:1.

-Ducky

Tang, Clayton (Yiqi) wrote:
I manage 250+ redhat linux boxes. The boxes are all setup the same way.
On a daily basis, we sync the app directory which is about 30gb out to
all hosts. The daily delta is actually less than 1gb, but since I can't
be sure if any individual box was tempered during the day, I always do a
full sync. On a monthly basis, we run with "--delete" to clean out the
stale files on the hosts.

The command I use daily is: "/usr/bin/rsync -a -e ssh", with a ksh for
loop on the 250+ host names
The version is: "rsync  version 2.5.7  protocol version 26"

Since rsync must do a chksum on the local and remote box on all files,
the whole sync process takes over 2hrs even if nothing was changed.

My questions are:

1) I know I have an old version, are there performance improvements in
the later versions? I am not the SA, the process to request a new
install is lengthy.

2) Is there a "parallel rsync" program? Looping 250 times to invoke
causes rsync to checksum the local files 250 times, which is a waste of
resource. Can "parallel rsync" be considered for a future version?

3) Are there better ways to achieve what I need to do with rsync or
another tool?

Thank you,
Clayton

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