Continued from Page 1
A short note about the backup devices. Linux, by default, has
support for SCSI tapes. The device /dev/st0 indicates the first such tape drive attached
to your system. If you’d use mirroring across disks, you’ll see devices like
/dev/md0, /dev/md1, etc, which are logical devices that represent a file system that
points to two physical disk partitions that are mirrored.
Now, let’s look at what utilities to use when you do not use
mirroring. I’d advocate the use of cpio to copy files from one disk to another. One
single command does all, elegantly. Here’s a typical command that you’d use to
copy the directory structure under /export/users to /spare/backup/users
backup.daily
#!/bin/sh
# Dump thingie
# Do incremental backups either to tape that is already in the remote
# tape drive or onto a spare disk that is mounted locally; it is assumed that
# these archives will be written to tape later.
#
if [ ‘echo $#‘ -ne 1 ]; then
echo "Usage: $0 [disk] [tape]"
exit
fi
#
BASE=/usr/local/bin
now=‘date ‘+%b %d %T %Y’‘
nowfile=‘date ‘+%b%d%Y’| tr -d ‘\040*’‘
then=‘cat $BASE/date.last.dump‘
if [ ‘echo $1‘ = "disk" ]; then
DEVICE=/mnt/backups/$nowfile.tar.gz
echo "Backing up to "$DEVICE"; Check if the backup partition is mounted in
/mnt"
echo "Enter to continue; ^C to abort"
# The mount check for the partition can be automated too; for the present,
# do it one at a time, abort and restart.
read x
else
DEVICE=root@dumpyard:/dev/st0
echo "Backing up to "$DEVICE"; Assuming tape is loaded"
read x
fi
#
HOME=/export/home
#
cd $HOME
#
FILES="*"
# Update FILES as required
#
/usr/sbin/tar -z -c -v \
-f $DEVICE \
-N "$then" \
-V "Dump from $then to $now" \
$FILES >/tmp/backup.log.$nowfile
echo $now > $BASE/date.last.dump |
# cd /export/users; find . -name -depth | cpio -pldmuv
/spare/backup/users/
You could similarly create a cpio archive by specifying a tape
device instead of the destination directory.
A variation of the same using the (GNU) tar is
# cd /export/users; tar zcvf /dev/st0 * >/tmp/backup.log.DDMMYY
dd is typically used in conjuction with cpio or tar.
# cd /export/users; tar zcvf - * | dd of=/dev/st0
is equivalent to the earlier command. To backup on a remote system,
use either of
# cd /export/users; tar zcvf backups@remote.host.name:/dev/st0 *
(Backup onto tape device attached to host remote.host.name on which
userid "backups" has permissions to allow remote command execution from userid
root on your machine.)
Page(s) 1 2 3 4 5 |
| 
