1 itec 400 Backups George Vaughan Franklin University

2 Topics Determining Backup Needs Backup Strategies Data Verification Storage Backup Media

3 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

4 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?

5 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?

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

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

8 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

9 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.

10 Multi-level backup SunMonTueWedThurFriSat Level 0: First Sunday of Month Level 1: Every Monday Level 2: Every Tuesday through Friday If I accidentally deleted my directory on the 25 th, which backups do I need?

11 Data Verification You never know how good your backups are until you need to restore. You can’t 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

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

13 Organization of Backups Labels –Color Coded –Printed Dedicated Shelf Location –By Day of Week? –By Week of Month? 3 rd Party Software –Stored separately?

14 Backup Media TypeCapacity (GB)Media Price ($) ($)/GBDrive Price ($) Mammoth Tape mm Tape AIT Tape Hard Disk CD-R CD-RW DVD-R DVD-RW Zip Disk Zip Disk Jazz Disk Jazz Disk Floppy

15 Backup Tools Tools/Commands to facilitate backups: –tar –cpio –dump/restore –amanda

16 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

17 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”

18 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

19 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

20 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 > 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”

21 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’ < myDir.cpio

22 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

23 Example of dump/restore 0009: dump -0 -u -f /backup/home_0 /home 0010: DUMP: Date of this level 0 dump: Mon Mar 10 23:08: : 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 23:08: : DUMP: Date this dump completed: Mon Mar 10 23:10: : 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

24 Example of dump/restore 0031: # cat /etc/dumpdates 0032: /dev/hdb2 0 Mon Mar 10 23:08: : # dump -1 -u -f /backup/home_1 /home 0035: DUMP: Date of this level 1 dump: Mon Mar 10 23:14: : 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…

25 Example of dump/restore 0062: # cd /home 0063: 0064: # restore -i -f /backup/home_0 0065: restore > ls 0066:.: 0067: dummy/ dummy1/ gvaughan/ johnsonm/ lost+found/ 0068: 0069: restore > add dummy 0070: restore > 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 #: : set owner/mode for '.'? [yn] n 0076: restore > quit Line 62: cd to filesystem Line 64: restore for level 0 backup

26 Example of backup/restore 0082: # restore -i -f /backup/home_1 0102: # cat /etc/dumpdates 0103: /dev/hdb2 0 Mon Mar 10 23:08: : /dev/hdb2 1 Mon Mar 10 23:14: Line 82: Complete restore from level_1 backup. Lines : Look at contents of /etc/dumpdates

27 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.