a very dumb backup question
Eric_St...@kenokozie.com
using samba shares and nt backup software. In my ignorance as a newbie I
didn't know if sticking a tape drive in the servers and using tar to
perform backups would catch open files. In my somewhat lesser ignorant
state as a familiar freebsd guy, I still don't know so I figured I'd ask.
Will open files (web pages, etc) be backed up to tape using tar?
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Eric Stanfield, K2Access
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Mike Meyer
> I have a number of freebsd boxes up that I've been backing up over the wire
> using samba shares and nt backup software. In my ignorance as a newbie I
> didn't know if sticking a tape drive in the servers and using tar to
> perform backups would catch open files. In my somewhat lesser ignorant
> state as a familiar freebsd guy, I still don't know so I figured I'd ask.
> Will open files (web pages, etc) be backed up to tape using tar?
Yes, they'll be backed up. Whether or not they'll be useful is another
question, that depends on what's going on in the open file.
This is the reason for wanting a file system quiescent when you back
it up. Historically, you do backups in single user mode to insure
that. Practically, the open files will have dates more recent than the
backup date after it finishes, so it's reasonable safe for
incrementals so long you don't hit the case some file being open
during backups every day.
Final comment - I'd recommend dump instead of tar, especially for the
root file system, because historically it's tracked changes to the
file sysystem and special files better than tar.
<mike
--
Mike Meyer <m...@mired.org> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.
bdlu...@heitec.net
[...]
> Final comment - I'd recommend dump instead of tar, especially for the
> root file system, because historically it's tracked changes to the
> file sysystem and special files better than tar.
I've got an additional question concerning dump vs. tar: I seem to
remember that tar has an built-in limit of 8 GB per single backup,
because of some restriction in the tar file format. Is this true, and
what are the limits for dump and pax? And, given that backups sizes are
limited, how to best backup a 30 GB partition using 20 GB tapes?
Chunk-wise, with several 'tar' runs to the same tape without rewinding,
I assume? (Repartitioning into partitions with less than 8 GB each is
not an option in my situation, I'm afraid.)
Is there a way to let 'dump' backup less than an entire partition, such
as a directory and all its subdirectories?
Mike Meyer
> Mike Meyer wrote:
> [...]
> > Final comment - I'd recommend dump instead of tar, especially for the
> > root file system, because historically it's tracked changes to the
> > file sysystem and special files better than tar.
> I've got an additional question concerning dump vs. tar: I seem to
> remember that tar has an built-in limit of 8 GB per single backup,
> because of some restriction in the tar file format. Is this true, and
> what are the limits for dump and pax? And, given that backups sizes are
> limited, how to best backup a 30 GB partition using 20 GB tapes?
> Chunk-wise, with several 'tar' runs to the same tape without rewinding,
> I assume? (Repartitioning into partitions with less than 8 GB each is
> not an option in my situation, I'm afraid.)
The limit on FBSD tar is 2GB. The gnu tar in the ports may have a
larger limit. I have no idea about cpio or pax; if you test them to
find out, please let us know.
Dump is designed for dumping large file systems to smaller tapes. If
you point it at a tape device, it will autodetect the end of tape (if
the tape device supports it, if not you have to tell it), and prompt
the operator to load another tape to the device.
> Is there a way to let 'dump' backup less than an entire partition, such
> as a directory and all its subdirectories?
Nope. That provides a reason for creating partition - because you use
dump, and want different backup strategies for two directories.
<mike
--
Mike Meyer <m...@mired.org> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.