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Desmond: Out-Tridging Tridge

Desmond: Out-Tridging Tridge

Posted Aug 28, 2013 21:51 UTC (Wed) by marcH (subscriber, #57642)
In reply to: Desmond: Out-Tridging Tridge by Pc5Y9sbv
Parent article: Desmond: Out-Tridging Tridge

This look like a very simple and efficient solution and simple is always good.

In fact I thought rsync was doing by default exactly what you described as --cow. And then I was wondering how come rsync was "defeating btrfs’ copy-on-write benefits"!

Note this good laugh from the original article: "The thing is, modern networks aren’t like that at all, they’re high bandwidth and low latency."

More seriously rsync could also feature a "--datacenter-network" recursive copy option that would do a plain, complete transfer of the files which have changed.


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Desmond: Out-Tridging Tridge

Posted Aug 28, 2013 22:16 UTC (Wed) by raven667 (subscriber, #5198) [Link]

> More seriously rsync could also feature a "--datacenter-network" recursive copy option that would do a plain, complete transfer of the files which have changed.

I thought that --whole-file option already did that

One thing about the rsync protocol is that it is disk IO expensive on _both_ ends to save network bandwidth, so when using rsync for backups issues on the backup server are more noticeable than the issues distributed out among the client population, especially when running multiple backups in parallel. The btrfs COW problems are a corollary to that, on the clients which are being read or among individual servers doing file transfers isn't not a problem, when collecting rsyncs from many servers all the sudden this issue is a noticeable problem.


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