Working with the Unix OS

Unix Administration
free -p /usr/local/bin /dev/rmt0 21:adm
volcopy /usr/local /dev/dsk/0s5 tape1 /dev/rmt0
! Backup Strategies
Unix dump has a "level" option for control of incremental backups.
Level 0 is a full backup
Level 1 is a incremental since the last level 0
Level 2 is a incremental since the last level 1 or 0
Level 3 is a incremental since the last level 2, 1 or 0
:
Level N is a incremental since the last level < N
Example Strateqy:
Full backup is done every week.
Incremental backups are done every day.
Mon 0
Tue 1
Wed 2
Thu 3
Fri 4
Another Example:
Week-1 0
Week-2 1
Week-3 2
Week-4 1
Week-5 3
Week-6 1
Week-7 2
Week-8 1
Week-9 0
This permits recovery of files lost anytime over the past 8 weeks.
We can combine these two strategies using levels 4, 5, 6, 7 during Tuesday to Friday and performing levels 0..3
each Monday.
Boot up & Shutdown
Booting the System
- Specify the disk and partition to boot from
- Unix kernel is loaded from /unix
- Can specify if single user or multi-user. System maintenance for level 0 backups.
- If space permits, keep minimal root partition on another disk in case the primary disk fails
- Booting executes /etc/rc shell script to fire off lots of daemons and initialize things
- Can boot off tape if necessary
Shutting down
- /etc/shutdown - shuts down the system cleanly
- /etc/sync; /etc/halt - minimum after all users logoff
- /etc/init S - go single user
- /etc/reboot - shutdown and restart as, some versions do not sync
Does the systems administrator have to process more interrupts than an operating system?
UNIX Startup Sequence
Turn on peripherals, Turn on computer Start bootstrap from ROM
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