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CRU for Linux - Version 2.4 CRU is at its End Of Life and TOLIS Group no longer supports
or develops this technology. While you may use CRU for your crash recovery model, users looking
for a crash recovery tool on Linux are suggested to use Mondo
Rescue What is CRU for Linux? CRU for Linux is an automated crash recovery utility for Intel-based (x86) Linux systems that is developed as a companion program for TOLIS Group's BRU Software. CRU for Linux is specifically designed for simplified full-system recovery. Providing a self-contained boot environment, a straight-forward user interface, and working in conjunction with BRU, CRU for Linux allows you to restart and recover from a total system crash by utilizing a specialized, BRU-based backup operation that fully automates the recovery of the crashed system and restores critical information in its entirety. Settings such as OS and hard disk configuration, network settings, tape drive and special SCSI device drivers, and filesystem data are returned to pre-crash operational status through the use of a standard BRU full system backup tape. CRU for Linux also includes mechanisms for remote recovery via network (telnet) or modem connectivity. In addition, CRU for Linux supports Hewlett-Packard's One-Button Disaster Recovery (OBDR) technology, enabling users to create a single tape capable of booting and restoring the entire system with the push of a button. What are the System Requirements?
What versions of Linux Does CRU Work With? CRU for Linux has been tested on SUSE, TurboLinux, Caldera, Mandrake, Slackware, Debian, and Red Hat systems, but should work with all x86-based Linux systems.
As of version 2.4.7, CRU for Linux supports software RAID (the md devices). However, we are unable to support hardware RAID as the version of sfdisk being used will not automatically generate a partition table on the /dev/cciss devices. As an option, since CRU is open source, if you have a Mylex, Adaptec, or DPT RAID controller, and know how sfdisk works, please feel free to help accelerate this project by submitting patches for a version of sfdisk that works for you. We are using the standard version of sfdisk from the utils-linux package. What Must I Know to Use CRU for Linux? If your system autoloads networking or tape device driver modules, you should know how to manually "insmod" or "modprobe" them to avoid having them unloaded during the various steps that CRU takes to create boot and root diskettes or OBDR tape. If an older ISA network adapter (NIC) is being used, you must know the I/O port address to enable networking when running CRU for Linux in recovery mode. Check your current module processing to see how this is configured on your system. How Does CRU for Linux Work? CRU examines the various system settings required to return your Linux system to an operational state from a bare metal (new hardware) situation and creates a pair of boot and root floppies that can be used to fully automate (in most instances) the system recovery process. With the addition of a tape drive with HP's ODBR technology, the creation of the boot and root floppies can be bypassed and the full recovery operation can be performed from a special OBDR recovery tape. Using either method, a newly built replacement system can be taken from its bare metal state to full operation by rebooting using the floppies or OBDR tape and selecting from the menu presented. Creating Recovery Diskettes/CRU Backup Tape CRU for Linux can be used to create two recovery diskettes: a boot diskette containing a special Linux kernel, and a root diskette containing a compressed RAM disk image. These diskettes are used to boot the system into a state that will allow full system recovery from a total system crash using a special CRU for Linux backup tape(s). During the diskette creation, CRU for Linux will attempt to locate any special device drivers that are required by the system to access all local hard drives, tape drives, and network cards. If CRU locates network cards, all of the proper network settings, such as IP address, netmask, broadcast address, and nameserver, will be stored for proper initialization when the system is booted from the boot and root diskettes. Once the disks have been created, CRU can be used in conjunction with BRU to create specialized, full-system backup tape(s) for use during recovery. While this backup provides full coverage for disaster recovery, unless you are performing full system backups daily, we recommend that you continue with your normal daily backups in addition to a weekly or monthly CRU full backup. Creating on OBDR Tape* On systems that have HP OBDR-capable tape drives, CRU for Linux allows you to create a single magnetic tape that can be utilized to restore the entire system with the push of a button (hence the classification "One Button Disaster Recovery"). With OBDR, your tape will contain an operational boot sector, all system configuration settings, all directory information and content, and will be capable of starting and completely restoring the machine directly from the OBDR drive.
Before You Begin Thanks to the variety of Linux distributions and standards, certain system variables that affect operation may be present that concern only the version of the operating system in use and do not have a widespread impact on other configurations. There may also be solutions that can be applied to a specific OS but are not functional with other operating system versions. As mentioned previously, there are several utilities that are critical to the operation of CRU, and it is wise to ensure that these are all in place before attempting to install or backup CRU. Any exclusion of these may ultimately result in a system that cannot be booted and/or recovered at all.
Note: While in many cases the aforementioned utilities are installed automatically, this is based on the presumption that the system's original OS installation was at least a "standard" install. Additional problems may result from working within the confines of a "minimal" OS package, as other necessary components may be excluded. READ THE FOLLOWING OS NOTES BEFORE INSTALLATION! CRU/OS Notes Known Issues and Limitations
Installation and Getting Started CRU for Linux is currently shipped on a CD-ROM in tar.gz format or is available for download as a single tar file from TOLIS Group's website. The following steps outline the correct installation procedures for both media types. All installation procedures and subsequent CRU operations should be performed from the Linux non-graphical runlevel "init 3" (init 2 for SuSe). NOTE: If a previous version of CRU has been installed on the system, enter the following command string to remove it BEFORE installing CRU v2.2:
Installation procedures for CRU from CD-ROM: 1. Login as root Correct installation for downloaded tar.gz file: 1. Login as root *The simplest way to test for the version of BRU that is installed is to enter bru -h at the command prompt, which will invoke a BRU summary. Also, similar to the XBRU graphical interface, utilization of CRU's OBDR option requires that a non-rewinding device be present in /etc/brutab. Before operation, ensure that there is a non-rewinding device correctly listed in the brutab. CRU should default to the device automatically when the OBDR option is selected. When using CRU with floppies, the default should be the non-rewinding device, as well. Once installed, test CRU for Linux by typing 'cru' at the command prompt on the console screen. The display should look like this:
As shown in Figure 1, CRU for Linux is a simple, three-option* product. Either the boot and root diskettes may be created, a CRU-specific full system backup can be performed, or an OBDR tape can be created. Once again, for OBDR operation the system must be OBDR-capable and have mkisofs installed or the OBDR operation will fail. mkisofs is available as part of most major Linux distributions or as a download. If mkisofs is not installed on the system and OBDR is selected as an option, CRU will detect this and a warning message will be displayed before the backup can be created. *If your drive is NOT OBDR-capable, the third menu option ("Create One-Button...etc.) will NOT show up on the menu. Network Configuration Information Before making a menu selection, be aware that the diskette creation process should be fully-automated unless a kernel-based (non-modular) network adapter (NIC) driver is in use. Due to the manner in which different drivers are designed, there is really no consistent way to detect the NIC type. Subsequently, CRU for Linux will provide a list of the supported NIC drivers and the proper card must be selected from the list. At this point, it is necessary to know which driver the kernel is using. Refer to the settings in your kernel configuration or query whomever may have been responsible for building the system kernel. If you are not interested in setting up networking to provide remote access to the system, skip this step by answering "No" when asked (see below) about including network support. CRU for Linux has determined that you have networking enabled, but is unable to determine which NIC driver is in use. Would you like CRU to include networking support [y/N]? If you answer "Yes" to this prompt, the correct card type must be selected from a list similar to this: Please select the proper NIC driver from the following list: Keep in mind that an improper selection here will prevent networking from operating correctly when the CRU for Linux disks are booted. CRU for Linux Boot and Root Disk Creation Select Option "1" to create the CRU root and boot diskettes. This will require two blank, formatted 3-1/2" floppy disks. TOLIS Group strongly recommends using only new disks for this task to ensure the highest level of data integrity. The process is completely menu-driven and will guide you through with step-by step procedures. Follow the instructions carefully and label the disks as instructed. Creating the CRU for Linux backup After the boot and root diskettes are completed, a backup must be created that will constitute a full
system recovery. It is extremely important that this backup be performed according to the method in the "cruback"
script (in other words, do not try to substitute another backup) or there is potential that a full recovery
after a hard crash may not be possible. Select Option "2" on the CRU for Linux Main Menu (see
Figure 1) for step-by-step instructions. Once the backup has been completed, label the tape(s) as recommended
and store them in a safe location with the boot and root diskettes. Note: With some Linux distributions, the system may try to mount the current filesystem before creating the backup tape. If the message "Remounting volumes...mount: RPC: Program not registered" appears above the "Insert new tape..." line, this can be ignored. Be aware that a message will also appear following the backup tape creation that tries to unmount the same filesystem (thus is the one that you are currently using). This can be ignored, also. Creating an OBDR Tape Selecting option "3" from the Main Menu will allow you to create an OBDR tape that encompasses
all the capabilities of the CRU boot diskette, root diskette, and backup, and will enable you to completely
recover your entire system from a single magnetic tape. Once again, keep in mind that this option will
NOT be available if your machine does not have a functional OBDR drive installed. Visit HP's website
for more information on
OBDR After selecting option "3", follow the step-by-step instructions that are displayed and CRU
will carefully guide you through the OBDR process. You will again be prompted to choose the network status,
but most functions are automatic or require nothing more than a yes/no response. Once the tape has been
actuated, continue until you have gone through the initialization process and CRU is proceeding with
the BRU backup. The creation of the BRU backup can run for quite some time (i.e. 30 mins. or more) depending
on the size of the media being stored. Once the backup has completed, BRU will also begin a verification
pass to ensure data integrity. This should take just slightly less time than the backup. CRU for Linux's main purpose is to fully recover a crashed system. Recovery steps have been minimized so that the "Automatic Recovery" option can be utilized and a system can be successfully recovered by even the least-experienced of users. When a system has been rebooted using the CRU for Linux boot and root diskettes, the following menu should appear:
The simplest recovery option at this point is Option "1" which, when chosen, will have CRU automatically rebuild the disk partitions, make the swap and filesystems, and restore the CRU for Linux backup that you previously created. This process requires only that the system drive(s) be the same size or larger than the drive(s) installed when the CRU for Linux boot and root diskettes were created. If any drive size has been changed, it is still possible to recover the system using CRU for Linux. However, there may be steps that will have to be performed manually. NOTE: Prior to remaking the Linux filesystems, you will be queried as to whether or not CRU should perform a badblock scan on the hard drive. We strongly recommend answering "yes" to this question, as a "no" answer could, unbeknownst to the user, result in data being written to inaccessible or "bad" areas of the hard drive, which could lead to severe system instability after booting. Recovering a System Using a CRU for Linux OBDR Tape When using an OBDR tape, first ensure that the system is powered down. Once you have verified the power status, turn the system on and proceed with whatever steps are necessary to initiate the tape drive's OBDR mode (i.e. holding the eject button down for 5 seconds while powering up the drive). Check your OBDR documentation if you are confused about this process. The system should then boot to the OBDR configuration and, once loading has completed, display the CRU menu. Option "1" will allow you to initiate the automatic recovery process. Using Expert Mode Option "2", the "Expert Mode", will provide full, root-level access to the targeted system. Before this option is selected, please be aware that you will be operating as root on a RAM disk, which allows you to perform functions that can ultimately prevent proper recovery of the system. Before continuing, make certain that you are aware of all of the processes involved with root-level access to a Linux system. CRU for Linux provides the root level user with a full set of system maintenance tools. The default shell is "bash". Included in the root filesystem are the following:
Enabling Network Access If networking was enabled during the creation of the CRU for Linux boot and root diskettes, the active settings were written to the root filesystem. By selecting Option "3", these settings are enabled and others will then be allowed access to the system. Because the access granted when networking is enabled is uncontrolled, root-level access, this option is disabled by default. Once selected, the menu will change and the IP address of the system will be displayed. This is especially useful for providing a remote technician with the proper information for directionalizing their telnet client. Once enabled, the following menu should appear on the other end of the telnet:
From this menu, a remote administrator can perform all of the required steps, whether automated or manual, to properly reconfigure and recover a system. Once someone has been logged in through the telnet protocol, no other users can access the system in that manner. Keep in mind, however, that the same caution applies to Expert Mode logins from a remote telnet session as from the local console. This will initiate root-level access with all the inherent dangers. Enabling MODEM Access Selecting Option "4" from the main menu (Figure 2), will have the system enable the primary serial ports for dial-up access. You will need to know the phone number of the MODEM to access the system. Once enabled, the system will set up an agetty process with autobaud and a generic HAYES®-compatible initialization string. Once a MODEM connection is made, the calling end will be greeted with the same menu as a telnet user (and the same warnings apply!). Networking/Modem Options To provide access security, the default settings for networking and modem options are set to "OFF". Since anyone connecting to a system through these services has full access to the system, some level of access control needs to be in the hands of the system owner. Until the console operator enables one of these options, the only access is local. |
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