Backup3G FAQ

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Revision as of 00:17, 5 July 2006

Backup and Recovery

How do I perform a recovery from a backup without the COSmanager Framework?

Performing a restore without COSmanager can be easily accomplished as all backup methods provided make use of common Unix commands. The formats involved are cpio, tar and dump. However, because of the flexabilty in setting up backups through COSmanager, a backup may be comprised of multiple format tape files, and even accross multiple volumes. Then the main issue in recovering files at the command line level is not so much knowing the commands, but knowing what the layout of a given tape, or set of tapes is. Following are the commands required to recover in full a tape file as backed up using a provided backup method.

Recovery Commands

Let us assume that the format and layout of the backup tape is known. Firstly you need to change directory to the base directory you are about to recover.

cd <base directory>

Secondly, you need to skip to the to the beginning of the appropriate tape file. Remember that the electronic media label is the first tape file. For example, you need to recover /usr which is the third step in your backup, therefore you need to skip to the beginning of the fourth tape file.

mt -f <no-rewind device> fsf 3 

or

mt -t <no-rewind device> fsf 3if 

on HP/UX or

dd if=<no-rewind device> of=/dev/null 

three times. Then recover the tape file according to the backup format as follows. For the standard cpio backup using the FS-wrapper FScpio use the following command to recover in full:

dd if=$Device_nr ibs=<bs> | cpio -icdum 

For the standard tar backup using the FS-wrapper FStar use the following command to recover in full:

dd if=$Device_nr ibs=<bs> | tar xpf - 

For the standard dump backup using the FS-wrapper FSdump use the following command to recover in full:

dd if=$Device_nr ibs=<bs> | ufsrestore xf - 

for SVR4 versions of Unix, or

dd if=$Device_nr ibs=<bs> | restore xf - 

for SVR3 and Berkley versions of Unix. Where <bs> is the blocksize associated with the media type multiplied by 1024. For example, if your DAT media type has a blocksize of 32 kbytes associated with it then <bs> will be 32768.

How do I print a catalogue of my backup tapes?

COSmanager can simplify this by automatically printing a log of a media set contents immediately after a backup has completed. To do this place the following command in the At-end cmd for the backup job definition.

( medrep -d 0 ; FSdrive $Drive list ) | asuser fsadmin $PRINTCMD 

Or you can key in the script shown at the end of this section called ~fs/FSadmin/local/bin/medcat and use the following command in either the At-end cmd or the At-unload cmd of the backup job definition. Remember to make the script executable.

( banner $Set_ID ; medcat $Set_ID ; FSdrive $Drive list ) | asuser fsadmin $PRINTCMD 

An example of this media contents log is shown below. The printout also shows the tape drive operations commands for the backup drive. Knowing these and the devices involved will be useful when, for example, you need to recover /var/spool - the fifth tape file.

Media written in the last 0 days. #1054DAT-hiWritten: 17/08/94Expires: 24/08/94Location: FS
Full backup of gomez using portable cpio
File 217/08/94-00:01full dumpgomez:/
Full backup of /
File 317/08/94-00:13portable full cpiogomez:/usr
Full backup of /usr
File 417/08/94-00:18portable full cpiogomez:/opt
Full backup of /opt
File 517/08/94-00:53full targomez:/var/spool
Full backup of /var/spool
File 617/08/94-02:00 portable full cpiogomez:/local
Full backup of /local

Drivedat (Sun DAT unit)
TypeDAT-hi
Hostgomez
Device/dev/rmt/1
No-rewind device/dev/rmt/1n
Drive namedat
Operator messageDAT drive needs attention
Drive classmt_tape (Tape operations via MT(1) command)

----- Operations ----------------------------------------------------

Statusmt -f $Device_nr status
Rewindmt -f $Device_nr rewind
Skip forwardmt -f $Device_nr fsf $N
Skip backward mt -f $Device_nr bsf $N
Unload mediamt -f $Device_nr offline
Where $Device refers to the device /dev/rmt/1 above and $Device_nr refers to the no-rewind device /dev/rmt/1n. 
In the Skip  forward and Skip backward operation, $N refers to the number of tape files to be skipped.

Script ~fs/FSadmin/local/bin/medcat #! /bin/sh

#
#medcat.sh
#
#Copyright (c) 1991-1994 Functional Software
#All Rights Reserved
#
#Media reports
#
#ident@(#)medcat.sh1.1 (Functional Software - FSadmin) 94/08/30
#

USAGE="Usage: medcat Set_ID" 

if [ -z "$1" ]; then
echo $USAGE >&2
exit 1
fi

SORTPARMS="Written Set_ID Sequence File"
RPTPGM=msetrep.awk

db_sel media "Set_ID == \"$1\" && Usage != \"scratch\"" | \
db_join -n - medcont Number | \
db_sort - $SORTPARMS | \
db_rpt - $APPL_HOME/report/$RPTPGM

How do I accomodate for disaster recovery? (draft)

A backup must contain the following:

1. file system
2. COSmanager directory structure
3. audit trail directory /usr/spool/log

Have on hand the hardcopy catalogue of this tapes contents.

Initially recover the root file system, then COSmanager and the audit trail directory. See FAQ How do I perform a recovery from backup without COSmanager? to do this.

After recovering COSmanager, you must acknowledge the backup job that performed this backup so that the status tables are cleared. For version 2.4.x this done by performing the option Unload media from drive on the Manage removable media jobs menu. For version 2.5.x this is done by performing the option Acknowledge job completion on the Manage removable media jobs menu. This will return COSmanager to the status just after the above backup was completed.

You can now use COSmanager to perform the recovery of the rest of your system. This may mean applying incremental backups to full backups.

How do I perform an interactive dump recovery?

Setup new recovery method as follows:

Method:dump interactive
Description:Recover interactive from dump
Format:dump
Index Command:
Full Recovery:cd $Directory ; ufsrestore -ivf $Device_nr < /dev/tty
Selected Rcvry:
Use STDOUT?no
Remote support?no
Run on host:file_host

How can I get a report detailing steps of all backup jobs run across my Data Center?

Setup an at-request duty that calls the following script:

for host in `db_sel -h hostinfo "Admintype != \"\"" Hostname`;
do
for bujob in `FSremote $host "db_proj -h backup Job`;
do
echo "Host: $host\n\n"
FSremote $host "showback $bujob"
echo "\n\n"
done
done | scroll -H0

How can I get a background backup job to output the log to standard out?

Some people wish to capture the backup log to other than the log file itself. Either for it to be mailed to a user or to be captured by a task/batch scheduler system. This can be done by a minor change to ~fs/FSadmin/bin/FSbackup. Change the line (around line 206 in the background portion of the case statement)

setpgrp runback ${load_now:+-L} "$Drive" $ID "$Job" >$LOG 2>&1 

to

setpgrp runback ${load_now:+-L} "$Drive" $ID "$Job" 2>&1 | tee $LOG