LinuxTag2012 Rear
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The document provides best practices for Linux disaster recovery using the Relax and Recover (ReaR) tool, which focuses on business continuity planning and technical recovery strategies. Key elements include the installation of ReaR, backup strategies, creating rescue media, and the recovery process. Recommendations emphasize simplicity, reliability, cost-effectiveness, and thorough documentation to ensure effective disaster recovery.
![Installation of rear
● E.g. on Fedora 17
# yum install rear
Installing:
rear noarch 1.13.0-1.fc17 fedora 327 k
Installing for dependencies:
at i686 3.1.13-7.fc17 fedora 61 k
bc i686 1.06.95-6.fc17 fedora 106 k
binutils i686 2.22.52.0.1-5.fc17 fedora 3.6 M
ed i686 1.5-3.fc17 fedora 72 k
ethtool i686 2:3.2-2.fc17 fedora 93 k
genisoimage i686 1.1.11-10.fc17 fedora 338 k
….
Install 1 Package (+40 Dependent packages)
Total download size: 21 M
Installed size: 65 M
Is this ok [y/N]: y
● We also need syslinux (and to boot on USB: extlinux)
# yum install syslinux
● Install nfs-utils, cifs-utils, rsync if required
● Do not forget openssh(-clients)
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![Backup Types
● The major backup types available are
● NETFS: NFS, CIFS, USB, TAPE
● RSYNC: rsync method
● REQUESTRESTORE, EXTERNAL
● BACULA (open source backup software)
● DP, NBU, TSM, GALAXY[7] (commercial stuff)
● Some not (yet) implemented backup types (waiting on sponsors)
● NSR (Legato Networker)
● CDROM
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![Rear help
● Usage: rear [-dDsSvV] [-r KERNEL] COMMAND [--
ARGS...]
● Available options:
● -d debug mode; log debug messages
● -D debugscript mode; log every function call
● -r KERNEL kernel version to use; current: '2.6.42.3-
2.fc15.i686.PAE'
● -s simulation mode; show what scripts rear would include
● -S step-by-step mode; acknowledge each script individually
● -v verbose mode; show more output
● -V version information
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![Rear help
● Usage: rear [-dDsSvV] [-r KERNEL] COMMAND [--
ARGS...]
● List of commands:
– checklayout check if the disk layout has changed
– format format and label media for use with rear
– mkbackup create rescue media and backup system
– mkbackuponly backup system without creating rescue media
– mkrescue create rescue media only
– recover recover the system; only valid during rescue
– savelayout save the disk layout of the system
– shell start a bash within rear; development tool
2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 16](https://image.slidesharecdn.com/ldrbestpracticesrear-13390509317581-phpapp01-120607013802-phpapp01/85/LinuxTag2012-Rear-16-320.jpg)
LinuxTag2012 Rear
- 1. Relax and Recover Linux Disaster Recovery best practices with rear Gratien D'haese IT3 Consultants
- 2. Who am I ● Independent Unix System Engineer since 1996 ● Unix user since 1986 ● Linux user since 1991 ● Open Source contributor: ● Make CD-ROM Recovery (mkCDrec) ● Relax and Recover (rear) ● SIM Installation and Logging (similar) ● Adhocracy (adhocr) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 2
- 3. Disaster Recovery ● Business Continuity Planning ● A business continuity plan specifies how a company plans to restore core business operations when disasters occur ● Disaster Recovery ● Disaster recovery looks specifically at the technical aspects of how a company can get back into operation using backup facilities 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 3
- 4. Disaster Recovery Concerns ● Uptime ● Quick restores with minimal or no manual steps after the recovery ● Reliability ● Avoid corrupted file systems and that system boots after recovery ● Cost ● DR solutions need to be affordable ● Complexity ● DR plans tend to be too complex. 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 4
- 5. Getting started with Relax and Recover (rear) ● Download it from ● The official tar-balls – https://github.com/rear/rear/downloads/ ● The rear-snapshot rpm's build from Github – http://download.opensuse.org/repositories/Archiving:/Backup :/Rear/ ● The official source – https://github.com/rear/rear ● The official repo's (Fedora, EPEL and SLES) – yum install rear – zypper install rear 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 5
- 6. Installation of rear ● E.g. on Fedora 17 # yum install rear Installing: rear noarch 1.13.0-1.fc17 fedora 327 k Installing for dependencies: at i686 3.1.13-7.fc17 fedora 61 k bc i686 1.06.95-6.fc17 fedora 106 k binutils i686 2.22.52.0.1-5.fc17 fedora 3.6 M ed i686 1.5-3.fc17 fedora 72 k ethtool i686 2:3.2-2.fc17 fedora 93 k genisoimage i686 1.1.11-10.fc17 fedora 338 k …. Install 1 Package (+40 Dependent packages) Total download size: 21 M Installed size: 65 M Is this ok [y/N]: y ● We also need syslinux (and to boot on USB: extlinux) # yum install syslinux ● Install nfs-utils, cifs-utils, rsync if required ● Do not forget openssh(-clients) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 6
- 7. Decide on DR strategy ● Which backup mechanism to use? ● GNU tar, rsync, bacula, commercial backup program ● Where will the backups reside? ● NFS share, CIFS share, external USB disk, tape, local spare disk ● Remote network location ● How shall we start the rescue image ● Via CDROM (ISO image), tape (OBDR), network (PXE), USB disk 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 7
- 8. Backup Types ● The major backup types available are ● NETFS: NFS, CIFS, USB, TAPE ● RSYNC: rsync method ● REQUESTRESTORE, EXTERNAL ● BACULA (open source backup software) ● DP, NBU, TSM, GALAXY[7] (commercial stuff) ● Some not (yet) implemented backup types (waiting on sponsors) ● NSR (Legato Networker) ● CDROM 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 8
- 9. BACKUP type NETFS pxelinux OUTPUT=PXE network BACKUP=NETFS isolinux OUTPUT=ISO (NFS|CIFS|local) extlinux disks External USB disks Tape drive OUTPUT=ISO OUTPUT=OBDR OUTPUT=USB BACKUP=NETFS BACKUP=NETFS BACKUP=NETFS 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 9
- 10. Location BACKUP_URL ● BACKUP=NETFS ● BACKUP_URL can be ● File type: BACKUP_URL=file:///directory/ ● NFS type: BACKUP_URL=nfs://nfs-server/directory/ ● CIFS type: BACKUP_URL=cifs://samba/directory/ ● USB type: BACKUP_URL=usb:///dev/sdc1/directory/ ● Tape type: BACKUP_URL=tape:///dev/nst0 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 10
- 11. Backup Program ● BACKUP=NETFS ● /usr/share/rear/conf/default.conf ● By default is BACKUP_PROG=tar ● However, BACKUP_PROG=rsync is possible for local attached storage ● BACKUP_PROG_COMPRESS_OPTIONS="-- gzip" ● BACKUP_PROG_COMPRESS_SUFFIX=".gz" ● BACKUP_PROG_EXCLUDE=( '/tmp/*' '/dev/shm/*' ) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 11
- 12. BACKUP_PROG_COMPRESS_OPTIONS 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 12
- 13. /etc/rear/local.conf ● Define your settings in /etc/rear/local.conf (or /etc/rear/site.conf) ● # grep -v -E '(^#|^$)' /etc/rear/local.conf OUTPUT=ISO MODULES_LOAD=( vmxnet ) ● Add: BACKUP=NETFS BACKUP_URL=nfs://server/path ● On NFS server backup => /path/$(hostname)/ 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 13
- 14. Rear dump ● View system configuration: # rear dump Relax and Recover 1.13.0 / $Date$ Dumping out configuration and system information This is a 'Linux-x86_64' system, compatible with 'Linux-i386'. System definition: ARCH = Linux-i386 OS = GNU/Linux OS_MASTER_VENDOR = OS_MASTER_VERSION = OS_MASTER_VENDOR_ARCH = OS_MASTER_VENDOR_VERSION = OS_ MASTER_VENDOR_VERSION_ARCH = OS_VENDOR = Fedora OS_VERSION = 16 OS_VENDOR_ARCH = Fedora/i386 OS_VENDOR_VERSION = Fedora/16 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 14
- 15. Rear help ● Usage: rear [-dDsSvV] [-r KERNEL] COMMAND [-- ARGS...] ● Available options: ● -d debug mode; log debug messages ● -D debugscript mode; log every function call ● -r KERNEL kernel version to use; current: '2.6.42.3- 2.fc15.i686.PAE' ● -s simulation mode; show what scripts rear would include ● -S step-by-step mode; acknowledge each script individually ● -v verbose mode; show more output ● -V version information 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 15
- 16. Rear help ● Usage: rear [-dDsSvV] [-r KERNEL] COMMAND [-- ARGS...] ● List of commands: – checklayout check if the disk layout has changed – format format and label media for use with rear – mkbackup create rescue media and backup system – mkbackuponly backup system without creating rescue media – mkrescue create rescue media only – recover recover the system; only valid during rescue – savelayout save the disk layout of the system – shell start a bash within rear; development tool 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 16
- 17. Disaster Recovery in Practice ● Gather system information ● Store the disk layout ● Partitioning, LVM and RAID configuration ● File systems, file system labels ... ● Boot loader (GRUB, LILO, ELILO) ● Make a system backup (OS and user data) ● Create boot-able rescue media with system configuration (and optional with backup data) ● All steps are done “online” online 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 17
- 18. Rear mkrescue ● Will create an ISO image stored as ● /tmp/rear-$(hostname).iso ● On NFS server as /path/$(hostname)/rear- $(hostname).iso ● Inspect file /var/lib/rear/layout/disklayout.conf ● Try to boot from the ISO image into the RESCUE system ● Use 'dmesg' to check if devices were found 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 18
- 19. Rear mkbackup ● Create rescue image with backup archive ● Do not forget to browse through the /tmp/rear-$ (hostname).log file for errors 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 19
- 20. Recovery Process in detail ● Boot system from rescue media ● Restore disk layout ● Create partitions, RAID configuration and LVM ● Create file systems (mkfs, mkswap) ● Configure file systems (labels, mount points) ● Restore the backup data ● Restore the boot loader ● Inspect & Reboot 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 20
- 21. Recover with rear (1) ● Boot rescue image and select 'recover' 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 21
- 22. Recover with rear (2) ● Wait until you see the login prompt 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 22
- 23. Recover with rear (3) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 23
- 24. Recover with rear (4) ● Ready? Reboot (shutdown -r 0) ● That's it – wait a while for the selinux relabeling ● Verify the restored system 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 24
- 25. Cloning with rear (1) ● Start the recover process: rear -v recover 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 25
- 26. Cloning with rear (2) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 26
- 27. Cloning with rear (3) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 27
- 28. Cloning with rear (4) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 28
- 29. Cloning with rear (5) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 29
- 30. Cloning with rear (6) So you better know what you're doing, right? The BACKUP variable was not set in the /etc/rear/local.conf configuration file! 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 30
- 31. Get your hands dirty? ● We hope you want to dig deeper into rear! ● Getting started: ● Use: rear -s mkbackup to see the flow of the scripts it will execute ● Depends on BACKUP method, architecture and OS version/brand ● Be careful: rear -s recover follows a different flow (seems logically, but you must understand the difference) 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 31
- 32. Where is the code? ● Main script is /usr/sbin/rear ● All the other scripts live under /usr/share/rear ● Documentation is at /usr/share/doc/rear-x.y.z ● Good news! It's all written in Bash 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 32
- 33. Where to put a script? ● mkbackup method: /usr/share/rear/... ● conf/ - configuration files (/etc/rear/*.conf read last) ● prep/ - preparation work; checking the environment ● layout/save/ - save the disk layout /var/lib/rear/layout ● rescue/ - modules, network, storage,... ● build/ - populate the initial ramdisk for our rescue image ● pack/ - create the initrd and copy kernel ● output/ - create the ISO image and copy to OUTPUT_URL ● backup/ - make the backup archive to BACKUP_URL 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 33
- 34. Where to put a script? (2) ● recover method: /usr/share/rear/... ● conf/ - read the configuration file + /etc/rear/*.conf ● setup/ - user defined scripts to run before recover ● verify/ - to check if a recover is possible at all ● layout/prepare – recreate the disk layout ● restore/ - restore the archive from BACKUP_URL ● finalize/ - do some dirty tricks for disks, grub,... ● wrapup/ - copy the recover log to /mnt/local/root/ 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 34
- 35. Example script: sysreqs.sh ● A simple script to save basic system requirements – sysreqs.sh ● OS version; rear version ● CPU, memory ● Disk space requirements ● IP addresses in use; routes ● Copy sysreqs.sh to a flow, e.g. rescue is a good choice ● # cp /tmp/sysreqs.sh /usr/share/rear/rescue/GNU/Linux/96_sysreqs.sh 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 35
- 36. Test the script ● # rear -s mkrescue | grep sysreqs Source rescue/GNU/Linux/96_sysreqs.sh ● # rear -v mkrescue ● # cat /var/lib/rear/sysreqs/Minimal_System_Requirements.txt fedora - 2012-05-22 11:26 Operating system: LSB Version: :core-4.0-ia32:core-4.0-noarch Distributor ID: Fedora Description: Fedora release 16 (Verne) Release: 16 Codename: Verne Relax and recover version: Relax and Recover 1.13.0 / $Date$ There are 1 CPU core(s) at 2393.832 MHz 748 MiB of physical memory Disk space requirements: OS (vg + swap + /boot) size: 6.09 GiB Network Information: IP adresses: ip 6 ::1 subnet /128 scope host DNS name ip 192.168.5.135 subnet /24 DNS name ip 6 fe80::20c:29ff:fe63:5cd0 subnet /64 scope link DNS name 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 36
- 37. https://github.com/rear/rear/issues 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 37
- 38. Contacts Web-site: http://rear.github.com/ GitHib: https://github.com/rear/rear Mailing list: [email protected] Rear Maintainer - Gratien D'haese - [email protected] Rear Maintainer - Schlomo Schapiro - [email protected] Rear Developer – Jeroen Hoekx - [email protected] Rear Developer – Dag Wieers - [email protected] 2012-05-23 | Gratien D'haese Linux Disaster Recovery best practices with rear 38