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ZFS Replication To the Cloud Is Finally Here and It's Fast (arstechnica.com)
New submitter kozubik writes: Jim Salter at Ars Technica provides a detailed, technical rundown of ZFS send and receive, and compares it to traditional remote syncing and backup tools such as rsync. He writes: "In mid-August, the first commercially available ZFS cloud replication target became available at rsync.net. Who cares, right? As the service itself states, If you're not sure what this means, our product is Not For You. ... after 15 years of daily use, I knew exactly what rsync's weaknesses were, and I targeted them ruthlessly."
rsync synchronises files. ZFS synchronises a file system. Of course it is better to work that way because you can transfer just the changed components of a file. Moving a file just changes a pointer, so send the pointer. That sort of thing.
http://michaelsmith.id.au
Reading this article, it seems that this "ZFS replication" is very similar to rsync, with one straightforward addition:
Rsync works on an individual file level. It knows how to synchronized each modified file separately, and does this very efficiently. But if a file was renamed, without any further changes, it doesn't notice this fact, and instead notices the new file and sends it in its entirety. "ZFS replication", on the other hand, works on the filesystem level so it knows about renamed files and can send just the "rename" event instead of the entire content of the file.
So if rsync ran through all the files to try to recognize renamed files (e.g., by file sizes and dates, confirming with a hash), it could basically do the same thing. This wouldn't catch the event of renaming *and also* modifying the same file, but this is rarer than simple movements of files and directories. The benefit would have been that this would work on *any* filesystem, not just of ZFS. Since 99.9% of the users out there do not use ZFS, it makes sense to have this feature in rsync, not ZFS.
there are things in this world that simply aren't meant for participation award winners. so go get offended somewhere else.
if somebody doesn't know what ZFS replication is, their product clearly isn't meant for them. why bother with explanation to a visitor that has no use for the product/service?
the attitude of these ZFS people is still quite welcoming compared to some connectivity providers i've dealt with. e.g. bogons.net will just politely tell you to f*ck off if you don't fully understand what you're purchasing from them (dwdm/cwdm rings).
their howtos hold newbies' hands sufficiently. they simply don't provide a free "Oracle ZFS Storage Appliance Administration course", which is what some people seem to expect. it seems i am discussing this with people who haven't even visited their website, so i'll stop here.
Anyone else getting tired of is term? All it means is "someone else's computer". All you're doing is renting server space and replicating your data there. There's nothing special about it.