Thursday, July 2, 2009

Performing File System Backups

Performing File System Backups

/dev/rmt/#hn -- h – Tape Density (l,m,h,c,u) n – no rewind

mt –f tape-device-name command count
mt status -- Displays status info about the drive
mt offline -- Rewind the tape and if appropriate takes the drive unit offline
mt rewind -- Rewinds the tape
mt fsf count -- Moves the tape forward count records

# mt –f /dev/rmt/0n fsf 2 -- Positions the tape at the beginning of the third tape record

Level 0 Monthly
M T W Th F
3 4 5 6 2
3 4 5 6 2
3 4 5 6 2

/etc/dumpdates -- Each line shows the FS that was backed up and the level of the last backup. Also shows the date, and the time of the backup
(eg) /dev/rdsk/c0t2d0s6 0 fri jan 4 19:12:27 2005

When an incremental backup is performed the ufsdump command consults the /etc/dumpdates file. It looks for the date of the next lower level backup. Then the ufsdump command copies to the backup media all of the files that were modified or added since the date of that lower-level backup. When the backup is complete, the /etc/dumpdates file records a new wntry that describes this backup. The new entry replaces the entry for the previous backup at that level

Options for the ufsdump command

0-9 Backup levels
v Verify, After the tape is written for any discrepancies occur
s Size estimate
l Autoload, you use this option with an autoloading tape drive
o Offline, When the backup is complete. Takes offline, rewinds, and if possible eject
u Updates the /etc/dumpdates file
n Notify. Sends messages to the logged-in users terminals who are member of sys group
f device Specify the device

Tape Backup

Become root user, switch to single user mode, and unmount the FS
# /usr/sbin/shutdown –y –g300 “System is being shutdown for backup”
# umount /export/home
# fsck /dev/rdsk/c0t0d0s7
# ufsdump 0uf /dev/rmt/0 /dev/rdsk/c0t0d0s7

Remote Backups

To perform remote backups across the network, the system with tape drive must have an entry in its /.rhosts file for every system that uses the tape drive

# ufsdump 0uf host2:/dev/rmt/0 /export/home

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