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On Sat, 7 Mar 2009 08:04:17 -0800 |
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Grant <emailgrant@×××××.com> wrote: |
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> I'm backing up numerous large files on another machine on my local |
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> network. I've only been using rsync, but it occured to me that I |
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> might be able to save some time and space if I incorporate tar and |
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> bzip2. How will rsync interact with those? If I turn the whole |
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> backup into a big tar.bz2, would rsync need to redownload the whole |
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> thing if I change one file? If so, maybe I should turn different |
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> groups of files into tar.bz2 archives so rsync only needs to |
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> redownload an archive if one of its files has changed? |
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It's not a default behavior, but there is an '--inplace' option. |
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Also,there is a '--compress' option, if the bandwith is the only |
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problem, otherwise you can use lzma (with normal-best ratio) to either |
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acheive much better compression than bzip2 or still slightly better |
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ratio with improved speed / less cpu time with 'lzma -1' (fast mode). |
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And if you're going to put a lot of files (like whole fs) into a |
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single tar just to transfer it to some remote destination, prehaps you |
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shouldn't be using rsync at all, since you'll end up reading all the |
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files anyway to create the tar. |
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Alternatively, you can save disk space on the source machine by piping |
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tar directly to destination, with compression either on the source to |
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lessen the banwidth, or on the remote to lessen the load on the source |
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machine cpu. |
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That said, you can also use tar to create (or pipe) incremental backups |
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- just the changes since the time last one was made. Tar can handle that |
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as easily as rsync does, since it checks what needs to be transferred |
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each time anyway. |
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-- |
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Mike Kazantsev // fraggod.net |