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Backups, Logging, Troubleshooting. Dates for Last Week of Class. Homework 7 Due Tuesday 5/1 by midnight Labs 7 & 8 8 is extra credit Due Thursday 5/3 by midnight No Late ones accepted Final – Thursday 5/3 6 – 9:30 in classroom open [book|notes|computer] will need working VM. Backups.
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Dates for Last Week of Class • Homework 7 • Due Tuesday 5/1 by midnight • Labs 7 & 8 • 8 is extra credit • Due Thursday 5/3 by midnight • No Late ones accepted • Final – Thursday 5/3 • 6 – 9:30 in classroom • open [book|notes|computer] • will need working VM
Backups • What to backup? • How often? • Where? • Don’t forget to test restores!!!
Backup Medium • 2nd Hard Drive • CDs, DVDs, Flash Drives • Tape • Another server • Online
Backup Utilities • tar • cpio • dump/restore • zip/unzip • dd • really, really expensive commercial ones
Logs • Controlled by 2 daemons • syslog – general logging • klogd – kernel messages
Syslog • Controlled by /etc/syslog.conf: # Log anything except mail of level info or higher. # Don't log private authentication messages! *.info;mail.none;authpriv.none;cron.none /var/log/messages # The authpriv file has restricted access. authpriv.* /var/log/secure # Log all the mail messages in one place. mail.* -/var/log/maillog # Log cron stuff cron.* /var/log/cron
Syslog Format • Basic syntax: codeword.priority location • Example: cron.* /var/log/cron
Syslog Codewords • auth – message from a user authentication program this used to be called security • auth-priv – private authentication program • daemon – any daemon not explicitly listed will generate a message under this category • kern – kernel messages through klogd • syslog – messages about the logging process itself • user – messages from application software started by a user • local0 through local7 – messages generated by Linux where the level is established by the Linux vendor local7 for instance pertains to boot messages • cron, lpr, mail, news – self explanatory
Syslog Priorities • From lowest to highest: • none - no priority • debug - log debugging messages used by programmers or testers of the software • info - log informational messages about what the program is doing • notice - noteworthy events • warning - potential problem events • err – errors • crit - critical error messages that will likely cause the program to terminate • alert - like crit except that the error can impact other programs • emerg - problems serious enough to potentially crash the entire OS
Syslog location • File: /some/path/to/file • Remote: @loghost
Troubleshooting • Log files in /var/ • man pages!!!! • apropos (man –k) – search man pages for matches • System monitoring commands – top, ps, etc
How to install? • Source • Download .tar.gz, extract, make, make install • Packages (2 biggest for Linux) • RPM – Redhat Package Manager • DEB – Debian Packages • Commercial Unix • bff for AIX – Backup File Format • dstream for Solaris - shar
Package Managers • CentOS Specific • rpm (command line) • yum (command line) • pirut (Graphical front-end to yum) • “Applications” → “Add/Remove Software”
yum • yum – Yellowdog Updater Modified • Used for installing new software • Used for removing old software • Used for updating current software
Make • Used to build software from source all: scheduler scheduler: scheduler.o g++ scheduler.o -o scheduler scheduler.o: scheduler.C g++ -c scheduler.C clean: rm -rf *o scheduler install: scheduler mkdir -p /usr/local/bin cp scheduler /usr/local/bin