Unison Support?

[adinb]

I'd like to throw support for Unison (client & server) into the hat. It's cross platform, similar to rsync, but easier to use, and has plenty of F/OSS implementations. Unison might really make mirroring a lot easier with the readynas.

-adin

[beq]

Thanks for the suggestion, I really like what I've read about it.

Uses the rsync block-level diff algorithm, but also supports 2-way sync directly, and supposedly can even merge changes at both ends into the same file!

And native binary available for Windows, so no need for Cygwin...

+1 !

Resources:

http://www.cis.upenn.edu/~bcpierce/unison/

http://blog.kowalczyk.info/articles/usingUnison.html

http://www.linuxjournal.com/article/7712

[adinb]

Yeah, the only downside is that it appears that the developers have decided to move on to other projects.

Hopefully someone motivated in the F/OSS community will pick it up, because it has some real potential.

-a

[dca]

I've started to use Unison to synchronize some directories and it works amazingly well.
I think it would fit perfectly well to the ReadyNas as it would allow one to synchronize many machines with one master (the nas), which is the recommended way to synchronize more than 2 hosts.

+1

[toreolsen]

An extra vote for Unison. It is a brilliant program for two way sync, uses the rsync algoritm to save bandwidth use and is cross platform. I would get a lot more use out of my ReadyNAS NV if it supported Unison.

[bthom]

Hello,

I also strongly encourage this idea. As it stands now, to do 2-way synchronization I have to use one of my Macs to provide the interface (it goes thru the NAS) b/c the NAS can't provide unison services directly.

Folks at Infrant ... is there an effort to incorporate a unison server into the Nas units? If so, what's the status on that?

Thx,

--b

[yoh-dah]

With RAIDiator 4 and SSH access, you can implement Unison service on the ReadyNAS.

[bthom]

Can you please provide more detailed information on how one would begin to go about doing this?

Do I need to compile things on the Nas to make this work? I get the impression that the Nas CPU is too slow to do much of that kind of thing (e.g. http://....).

Thanks a bunch,

--b

[yoh-dah]

Check out the ReadyNAS Beta Forum.

[bindertwine]

I checked with one of the Unison developers...although they may be working on other projects, they also use Unison on a daily basis, and things continue to get fixed. It's a good solution...if only I could get it to work with the ReadyNAS.

I tried it by mounting the ReadyNAS and running Unison in local mode, but since I'm running Mac OS X, I found:

1) Can't use SMB/CIFS, because resource forks and extended attributes are not supported

2) Can't use NFS, same reason

3) Can't use AFP, because there is a bug in the AFP implementation on the ReadyNAS that doesn't set permissions correctly in all cases.

The only way to use Unison right now from Mac OS X with a ReadyNAS is to set Unison to ignore permissions, and to run it locally with the ReadyNAS mounted as a network disk. Of course, if permissions matter to you, this could be an issue.

[magi]

Running it in local mode doesn't give you the performance benefit of the rsync/unison protocols though; it basically misses the whole point. Sure, for many of us, network bandwidth between our computers and the ReadyNAS isn't at a premium (so conserving that doesn't matter), but I'll bet that the ReadyNAS can checksum files locally faster than it can stream them over any of its file sharing protocols.

So back to getting Unison running on the ReadyNAS: very cool that Raidiator 4 is now (beta) available and allows us to run our own services. Anyone have info on toolchain/compilers for compiling Unison (or whatever) for the ReadyNAS?

[bindertwine]

Well, if dpkg is implemented on the readynas (I don't know), you can probably install it easily enough. After radiator 4 is released, I'd be willing to try it myself.

Although it isn't true that running unison locally misses the whole point - after all, you are still achieving file synchronization. It's just a whole lot slower than it ought to be. But better than nothing.

[bhoar]

I'll bet that the ReadyNAS can checksum files locally faster than it can stream them over any of its file sharing protocols.

I wouldn't take that bet.

-brendan

[magi]

I wouldn't take that bet.

Hey Brendan. Ever since you wrote that, I've been wondering if you're right... thinking you probably were, but I wanted to know for sure. So I had a mental note to actually test it, once RAIDiator 4 shipped.

I just finally updated to RAIDiator 4, and (with a not-too-carefully tuned setup, for example I'm using the normal ethernet 1500-byte MTU, not jumbo frames), I get around 25MB/sec reads. Running md5sum locally, I was able to checksum a 700MB file in 27 seconds. Running md5sum against the same file locally on the NAS, it took 67 seconds (barely 10 MB/sec).

So you're right, and I lost the bet: the ReadyNAS can drop packets on the wire a lot faster than it can checksum them with md5sum.

I don't know exactly how rsync computes checksums and whether it's more or less CPU intensive than md5, but in the spirit of things, you win and that makes running rsync/unison on the NAS a lot less attractive, assuming a fast network (if you were running across a slow link, then of course the link becomes the bottleneck instead of the ReadyNAS's CPU and the tables may turn).