1 itec 400 backups george vaughan franklin university
Post on 21-Jan-2016
227 Views
Preview:
TRANSCRIPT
1
itec 400Backups
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
Sun Mon Tue Wed Thur Fri Sat
1
0
2
13
24
25
26
27
8 9
110
211
212
213
214
15 16
117
218
219
220
221
22 23
124
225
226
227
228
• 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?
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?
• 3rd Party Software– Stored separately?
14
Backup MediaType 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
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 storagegzip 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 myDirtar 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 storagegzip 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 myDircpio -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 23:08:54 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 23:08:54 2003
0027: DUMP: Date this dump completed: Mon Mar 10 23:10:48 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
24
Example of dump/restore0031: # cat /etc/dumpdates0032: /dev/hdb2 0 Mon Mar 10 23:08:54
2003
0034: # dump -1 -u -f /backup/home_1 /home
0035: DUMP: Date of this level 1 dump: Mon Mar 10 23:14:32 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…
25
Example of dump/restore0062: # cd /home0063: 0064: # restore -i -f /backup/home_00065: restore > ls0066: .:0067: dummy/ dummy1/
gvaughan/ johnsonm/lost+found/
0068: 0069: restore > add dummy0070: restore > extract0071: You have not read any tapes yet.0072: Unless you know which volume your
file(s) are on you should start0073: with the last volume and work
towards the first.0074: Specify next volume #: 10075: set owner/mode for '.'? [yn] n0076: 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 23:08:54 2003
0104: /dev/hdb2 1 Mon Mar 10 23:14:32 2003
• Line 82: Complete restore from level_1 backup.
• Lines 102-104: 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.
top related