Linux System Administration Recipes A Problem-Solution Approach

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CHAPTER 4 ■ TAKING BACKUPS AND MANAGING DATA■ Note If you don’t want to have LDAP offline, you can use a slave server (see recipe 2-7) and either run thebackup off that or rely on the slave to pick up any LDAP requests that come in the interim.Finally, line 13 deletes any files in the backup directory that are more than 14 days old, whichprevents you from ending up with enormous stacks of old LDIF files. Line 14 copies the backup directoryto a shared directory on a different machine (here mounted as /shared/raid/server_backups). Thus, ifyour LDAP machine crashes altogether, you don’t lose the backup directory as well.Putting the script in /etc/cron.daily/ means it will automatically be run once a day (the default isfor this to happen overnight). Make sure it’s root-owned and executable (note also that the name needsto have no extension, as shown here, or it won’t be run by run-parts):chown root:root /etc/cron.daily/ldapbackupchmod u+rx /etc/cron.daily/ldapbackupFor Kerberos backup, save this script as /etc/cron.daily/krbbackup:01 #!/bin/sh02 dir="/usr/local/backups/kerberos/"03 file="kerbdumpfile"04 server="raidserver:/raid"05 mntdir="/mnt/"06 remotedir="server_backups/"07 mount -t nfs $server $mnt08 kdb5_util dump $dir$file09 cp $dir$file $mntdir$remotedir10 umount $mntdirAgain, lines 02–06 set up the variables. Line 07 mounts the remote server. You can use this method ifyou don’t want the NFS remote directory to be permanently mounted, or automounted, on the Kerberosserver. (You can make a similar change to the earlier LDAP backup script, if you prefer.)Line 08 dumps the Kerberos database using kdb5_util dump, and lines 09–10 copy the dump fileacross to the remote server and then unmount it.Again, make sure the script is root-owned and executable:chown root:root /etc/cron.daily/krbbackupchmod u+rx /etc/cron.daily/krbbackup4-6. Performing a Rapid Restore with Automated rsyncOne problem with a tape backup solution is that in the event of some kind of catastrophic data loss(machine or drive failure, for example), tapes can take quite some time to restore, especially for largedrives.It’s therefore a good idea to have, as well as your tape backups, some kind of mirror of importantdirectories. Obviously, if you have a RAID 0 machine, you have this automatically, but if you don’t (or if104Download at WoweBook.Com
CHAPTER 4 ■ TAKING BACKUPS AND MANAGING DATAyou would prefer that your mirror be on another machine or even at another site), you can set up yourown mirroring with rsync.In this case, let’s look at the case of a shared home directory at homeserver:/shared/home.The basic rsync command is as follows:rsync /dir/source /dir/destinationThis compares the two directories and copies across any files in /dir/source that are newer thanthose in /dir/destination. So, the first time it’s run, it will copy everything (and may take some time);thereafter, it copies only what has changed, thus saving both time and network capacity.That basic command synchronizes from one local directory to another local directory, but in fact/dir/destination can be on another machine:rsync /dir/source machinename.example.com:/dir/destination■ Note You can also reverse this:rsync machinename.example.com:/dir/source /dir/destinationwhich is useful for restore.rsync has numerous options, but these are the most useful ones:• -a: Archive, which both recurses over the directory structure and keeps fileattributes (ownership, permissions, edit times, and so on) intact.• -u: Update, which does not update any files that are newer on the destinationdirectory than on the source.• -z: Compress, which compresses during the transfer.• -v: Verbose, so you can follow what’s happening.• -L: Follow symlinks, copying the files that they point to in full, rather than usingthe default option of recording them as symlinks.• --delete: Deletes from the destination directory files that no longer exist on thesource directory.• -n: Does a dummy run but doesn’t actually transfer any files (useful with -v whentesting).So, if you have a backup drive available at backupserver:/shared/backuphome, you can back up yourshared home directory like this, logged in as root on homeserver:rsync -avuz /shared/home backupserver:/shared/backuphome105Download at WoweBook.Com
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Contents■About the Author .......
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■ CONTENTS3-7. Writing a Nagios P
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■ CONTENTS■Chapter 8: Using the
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■ CONTENTSAbout the Author■Juli
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■ CONTENTSAcknowledgmentsMany tha
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■ CONTENTSIntroductionThis book i
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■ INTRODUCTIONDownloading the Cod
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C H A P T E R 1■ ■ ■Saving Yo
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CHAPTER 1 ■ SAVING YOURSELF EFFOR
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C H A P T E R 2■ ■ ■Centraliz
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CHAPTER 2 ■ CENTRALIZING YOUR NET
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CHAPTER 6 ■ SECURING YOUR SYSTEMS
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C H A P T E R 7■ ■ ■Working w
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CHAPTER 7 ■ WORKING WITH APACHEOn
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CHAPTER 7 ■ WORKING WITH APACHEdi
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CHAPTER 7 ■ WORKING WITH APACHE4.
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CHAPTER 7 ■ WORKING WITH APACHE
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CHAPTER 7 ■ WORKING WITH APACHEAl
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CHAPTER 7 ■ WORKING WITH APACHE
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C H A P T E R 8■ ■ ■Making Be
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CHAPTER 8 ■ USING THE COMMAND LIN
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C H A P T E R 9■ ■ ■Working w
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CHAPTER 9 ■ WORKING WITH TEXT IN
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C H A P T E R 10■ ■ ■Things G
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CHAPTER 10 ■ THINGS GO IN, THINGS
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C H A P T E R 11■ ■ ■Tracking
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CHAPTER 11 ■ TRACKING DOWN BUGSTh
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CHAPTER 11 ■ TRACKING DOWN BUGS01
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CHAPTER 11 ■ TRACKING DOWN BUGS
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CHAPTER 11 ■ TRACKING DOWN BUGSTh
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CHAPTER 11 ■ TRACKING DOWN BUGSAn
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CHAPTER 11 ■ TRACKING DOWN BUGS#
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C H A P T E R 12■ ■ ■Managing
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CHAPTER 12 ■ MANAGING TIME AND PE
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APPENDIX■ ■ ■Perl TipsSee rec
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APPENDIX ■ PERL TIPS• Date::Par
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APPENDIX ■ PERL TIPSPerl Syntax N
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■ ■ ■Index■Symbols$CDPATH,
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■ INDEXenscript option (printing)
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■ INDEX■NNagiosadding hosts to,
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■ INDEXsyslogcentralized logging
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