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How to use 'cp' as a simple but reliable backup tool
Authored by: zkarj on Feb 17, '10 04:28:36PM

Some of you aren't understanding my situation. My photos are RAW files. Those files never change. It's one of the major points about RAW. So my requirement is far simpler than many people are assuming below. The process for copying is best illustrated thus:

"Is this file already on the target volume?"

If the answer is yes, ignore it. Otherwise copy it. That's it!

The problem with rsync is that it is capable of doing stuff to my source directory. Given the documentation is not easy to understand (for me at least), I opted for a command that I could be sure would not touch my source directory. Get your options wrong with rsync and you could end up deleting original files.

As for speed, it was whipping through all my 2009 photos in well under a minute before copying the new stuff. The speed of my network was the bottleneck, not the speed of the command.

So in summary. cp meets my requirements. Simple is often best. If someone would care to write *clear* documentation on rsync I might find a use for it. (In fact, I do use aRsync for another task, but that was also a voyage of fear.)



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How to use 'cp' as a simple but reliable backup tool
Authored by: Hal Itosis on Feb 17, '10 09:32:36PM
@zkarj:
The problem with rsync is that it is capable of doing stuff to my source directory. Given the documentation is not easy to understand (for me at least), I opted for a command that I could be sure would not touch my source directory. Get your options wrong with rsync and you could end up deleting original files.
The first presumption that cp gives is "I'm not endangering my source files". It copies from a to b. Period.

Sorry to join the mob but, I think the fear factor there is a bit exaggerated. There is only one rsync "option" which behaves that way... and it requires the user to type the following twenty one c.h.a.r.a.c.t.e.r.s:

--remove-source-files

Nothing ambiguous or mystical about that. So long as that exact string is not used... there's nothing to fear (as far as the source files are concerned).

Other than those comments, i thought your hint was fine (in the context of RAW files).

-HI-

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How to use 'cp' as a simple but reliable backup tool
Authored by: zkarj on Feb 18, '10 12:38:57AM

Not if you already know that fact. (And now I do, thank you.)

Once again - come at this with NO prior knowledge of rsync and its syntax. I honestly had no idea it existed before I tried to solve this problem. It's touted as a two-way syncing tool. Unless I understand it, I'm not trusting it to leave my source files alone.

I think you'd agree the prospect of deleting your only copy of a photo while intending to back it up is the definition of a pretty bad day.



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How to use 'cp' as a simple but reliable backup tool
Authored by: Hal Itosis on Feb 18, '10 08:35:14AM
@zkarj:
It's touted as a two-way syncing tool.
Two-way syncing tool?!? No... it's not. And this is the first time i've heard that particular misinformaton being touted. (if anything, people sometimes complain that rsync *doesn't* do bidirectional syncs). Perhaps you're thinking of of Unison.

Unless I understand it, I'm not trusting it to leave my source files alone. I think you'd agree the prospect of deleting your only copy of a photo while intending to back it up is the definition of a pretty bad day.
Folks are far more likely to accidently delete stuff by not properly escaping\ a\ space\ in some pathname, than risk their source files when running rsync (and somehow adding the --remove-source-files option by "mistake").

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