Re: dump & restore
Mario Olimpio de Menezes wrote:
> I'm trying to learn how dump and restore utilities work and I'm
>having not much success. I could do a dump of a filesystem using the line
>dump 0udf 61000 /dev/nst0 /tmp2, where 61000 is the density of my tape.
> If I do only this, I can restore /tmp2 without problems.
> How can I backup another filesystem to the tape? It's a 60m tape;
>/tmp2 is only 190MB and the filesystem I want to append is about 300MB,
>that is, there is free space!
> I have read the man pages but couldn't figure out how to do this.
I asked this question last year and got this response from Nathan E Norman
Ok. I grabbed a copy of the mag, and I'll quote out relevant bits. I
^^^ [Sys Admin]
don't work for the publisher or anything like that, but I like the
magazine ... it's ISSN 1061-2688, and they have a website at
www.samag.com (it's amazing what you can find out when you read all the
small print on the first page :) This is from the Nov 97, Vol 6, Num 11
At any rate, the author says the following command should work well for
Linux dump, and a 2 GB DAT tape:
/sbin/dump 0nufB /dev/st0 2048000 /usr
/sbin/dump 0nufB /dev/st0 2048000 /dev/sda2
"Without the 'i', 'd', or 's' options, Linux 'dump' will request tape
changes too early. By setting the 'dump' records ('B'), 'dump' will not
ask for a tape change until 2 Gb of data has been copied or end-of-media
is signaled. I have found the 'B' option to be more dependable than
using 'd' and 's'. ('dump' never seems to calculate the size properly.)
It should also be noted that the Linux version of 'dump' is a in-work
project. This means that there are still a few problems. Single dump
files spanning multiple tapes may not work properly. It has been
reported that files are sometimes left out. To avoid problems, make
sure to do a test run before committing to a schema." (page 37)
> Any help will be greatly appreciated. Suggestions on other methods
>of backup, too!
dump is for saving complete file systems on the local machine; it cannot
be used for NFS mounted file systems, or for DOS partitions either.
All other methods depend on creating a list of files or directories
to be saved:
find top-level_directories -xdev | cpio -oBH crc >/dev/st0
find top-level_directories -xdev | afio -oc 32768 -s 0 -T 3k -Z >/dev/st0
tar czf /dev/st0 top-level_directories
There are also the programs taper, which I have not used, and tob, which
is a front-end to afio.
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight http://www.lfix.co.uk/oliver
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