itec 400 Backups

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itec 400Backups

• George Vaughan
• Franklin University

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Topics

• Determining Backup Needs
• Backup Strategies
• Data Verification
• Storage
• Backup Media

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Determining Backup Needs

• Your Valuables (Data)
• research data
• billing, tax records
• customer data
• Your Insurance (Backups/Archives)
• cost (money, interference with operations)
• quality of insurance policy (backup process)
• speed of recovery
• type of disasters covered

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Determining Backup Needs

• Can you tolerate the loss of everything?
• Can you tolerate the loss of some filesystems or
  files? which ones?
• How often is this critical data changing?
• How long can you wait before it is restored?

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Determining Backup Needs

• How old can the restored version be (hours, days,
  weeks)?
• How much can you afford to spend on a backup
  strategy?
• Does your system need to be available 24x7?

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Backup Strategies

• Different Strategies may be applied to different
  filesystems.
• 2 Types of backups
• Full Backup
• Incremental Backup

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Backup Strategies

• Full Backup
• Backup everything
• Can take a long time
• Can consume a lot of backup media
• Simplest to restore from

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Backup Strategies

• Incremental
• only backup files that changed since some point
  in time.
• Faster Backups
• Less consumption of backup media
• More complicated restore process
• Still need to do full backup every once in a
  while

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Multi-level backup

• A popular strategy multi-level backup
• Level 0 Full Backup.
• Level 1 Incremental backup since last level 0
  backup.
• Level 2 Incremental backup since last level 1
  backup.

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Multi-level backup
Sun Mon Tue Wed Thur Fri Sat
1 0 2 1 3 2 4 2 5 2 6 2 7
8 9 1 10 2 11 2 12 2 13 2 14
15 16 1 17 2 18 2 19 2 20 2 21
22 23 1 24 2 25 2 26 2 27 2 28

• Level 0 First Sunday of Month
• Level 1 Every Monday
• Level 2 Every Tuesday through Friday
• If I accidentally deleted my directory on the
  25th, which backups do I need?

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Data Verification

• You never know how good your backups are until
  you need to restore.
• You cant wait till disaster hits only to find
  that your tape units were never working.
• Need to periodically check/verify backups
• against original files
• on alternative machines
• for backup media degradation

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Storage

• Where should you store your backups?
• Maybe store level 1 and level 2 in an alternate
  location?
• What about archived data?

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Organization of Backups

• Labels
• Color Coded
• Printed
• Dedicated Shelf Location
• By Day of Week?
• By Week of Month?
• 3rd Party Software
• Stored separately?

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Backup Media
Type Capacity (GB) Media Price () ()/GB Drive Price ()
Mammoth Tape 60.00 45.00 0.75 3700
8mm Tape 7.00 6.00 0.86 1200
AIT Tape 100.00 105.00 1.05 3900
Hard Disk 100.00 120.00 1.20 120
CD-R 0.70 0.85 1.21 150
CD-RW 0.64 1.00 1.56 150
DVD-R 4.70 8.00 1.70 400
DVD-RW 4.70 8.00 1.70 400
Zip Disk 0.25 12.00 48.00 140
Zip Disk 0.10 5.00 50.00 70
Jazz Disk 2.00 100.00 50.00 340
Jazz Disk 1.00 80.00 80.00 300
Floppy 0.00 0.25 178.57 10
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Backup Tools

• Tools/Commands to facilitate backups
• tar
• cpio
• dump/restore
• amanda

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tar

• tar - tape archive utility
• a tar file is a file that contains other files
  and directories, plus information about them,
  such as their file name, owner, timestamps,
  and access permissions.
• The archive can be another file on the disk, a
  magnetic tape, or a pipe. used to store and
  extract files from tarfile
• commonly used to for creating a tarfile on disk

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Example Creating a tar File

• Solaris example create a compressed tarfile
  containing the directory myDir
• First, create the tar file from the directory
  myDir
• tar cf myDir.tar myDir
• -Next, compress the tar file, for easier
  distribution and/or storage
• gzip myDir.tar
• -Finally we end up with a compressed tar file
  named, myDir.tar.gz

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Example Unpacking a tar File

• Solaris example create a directory from a
  compressed tarfile named myDir.tar.gz
• First, uncompress the the tar file
• gunzip myDir.tar.gz
• -Next, untar the file. This will result in a
  directory named myDir
• tar xf myDir.tar

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cpio

• cpio - copy in and out of archive
• copies files into or out of a cpio or tar
  archive
• cpio has three operating modes
• copy-out - copies files out to archive
• copy-in - copies files in from archive
• copy-pass - copies files from one directory tree
  to another without creating intermediate archive

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Example Creating a cpio File

• Solaris example create a compressed cpio file
  containing the directory myDir
• First, create the cpio file from the directory
  myDir
• find myDir cpio -o gt myDir.cpio
• -Next, compress the cpio file, for easier
  distribution and/or storage
• gzip myDir.cpio
• -Finally we end up with a compressed cpio file
  named, myDir.cpio.gz

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Example Unpacking a cpio File

• Solaris example create a directory from a
  compressed cpio file named myDir.cpio.gz
• First, uncompress the cpio file
• gunzip myDir.cpio.gz
• -Next, unpack the cpio file. This will result in
  a directory named myDir
• cpio -imd myDir lt myDir.cpio

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dump/restore

• The dump and restore commands are used
  collectively
• More sophisticated than tar, cpio
• Supports multi-level backups
• Records backup history in /etc/dumpdates
• restore supports interactive mode

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Example of dump/restore

• 0009 dump -0 -u -f /backup/home_0 /home
• 0010 DUMP Date of this level 0 dump Mon Mar
  10 230854 2003
• 0011 DUMP Dumping /dev/hdb2 (/home) to
  /backup/home_0
• 0025 DUMP finished in 39 seconds, throughput
  6498 kBytes/sec
• 0026 DUMP Date of this level 0 dump Mon Mar
  10 230854 2003
• 0027 DUMP Date this dump completed Mon Mar
  10 231048 2003
• 0028 DUMP Average transfer rate 2283 kB/s
• 0029 DUMP DUMP IS DONE

• Line 9 perform level 0 (full) backup of /home
  filesystem and store in file /backup/home_0
• Lines 10-29 output of dump

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Example of dump/restore

• 0031 cat /etc/dumpdates
• 0032 /dev/hdb2 0 Mon Mar 10 230854 2003
• 0034 dump -1 -u -f /backup/home_1 /home
• 0035 DUMP Date of this level 1 dump Mon Mar
  10 231432 2003
• 0060 rm -rf dummy

• Lines 31-32 Look at contents of dumpdates
• Lines 34-35 Perform level 1 (incremental) backup
• Line 60 The act of much regret

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Example of dump/restore

• 0062 cd /home
• 0063
• 0064 restore -i -f /backup/home_0
• 0065 restore gt ls
• 0066 .
• 0067 dummy/ dummy1/ gvaughan/
  johnsonm/ lostfound/
• 0068
• 0069 restore gt add dummy
• 0070 restore gt extract
• 0071 You have not read any tapes yet.
• 0072 Unless you know which volume your file(s)
  are on you should start
• 0073 with the last volume and work towards the
  first.
• 0074 Specify next volume 1
• 0075 set owner/mode for '.'? yn n
• 0076 restore gt quit

• Line 62 cd to filesystem
• Line 64 restore for level 0 backup

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Example of backup/restore

• 0082 restore -i -f /backup/home_1
• 0102 cat /etc/dumpdates
• 0103 /dev/hdb2 0 Mon Mar 10 230854 2003
• 0104 /dev/hdb2 1 Mon Mar 10 231432 2003

• Line 82 Complete restore from level_1 backup.
• Lines 102-104 Look at contents of /etc/dumpdates

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Amanda

• amanda - Advanced Maryland Automatic Network Disk
  Archiver
• Developed at University of Maryland
• Client/Server model
• Multiple clients can be backed up onto a single
  backup server.
• Uses a combination of full and incremental
  backups.