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Re: Monitor ongoing upload?
--As of June 29, 2014 7:48:19 AM -0700, jerry is alleged to have said:
The real problem here is that I really shouldn't change the data set
while backing it up, right? I really can't afford to have this data sit
without write access for multiple days. Totally impossible.
Yes and no... Yes, if you want a consistent point-in-time backup, you
can't modify it while it's backing up. No in that you can modify it and it
won't mess up tarsnap.
Tarsnap will behave like any other Unix program (on Unix, at least);
meaning that once it opens a filehandle the OS will hold that version of
the file around until it's done with it. It only ever reads one file at a
time, so each file will be backed up in the state it was when tarsnap got
to it. It won't know about added files after you start the backup, and it
will throw warnings about ones that leave but it doesn't die just because
of them.
So if you backup an in-use filesystem and create files in it, they will be
ignored for that backup. If you edit files, they may or may not be backed
up in the edited state. If you delete files, they may or may not get
backed up first. Depending on what you are doing, this may be acceptable.
(It's typically not for databases, but usually is for personal files.)
If I copy a snapshot off to another device or tar file, and then tarsnap
off of that, will the transfer-only-changes feature still work when I do
subsequent tarsnaps of the original data?
I believe so (I think tarsnap doesn't care about the file path, only it's
hash), but I won't say for sure.
Daniel T. Staal
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