ArGest Backup User Guide

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  5. Global brutab Parameters

Global brutab Parameters

Several BRU parameters are not specific to a device. These are global parameters and are specified in the brutab file in a form that is different from device parameters. Global brutab parameters are specified with names that are all UPPER CASE. Only one parameter is allowed per line. A line containing a global parameter must begin with the two-character sequence #+ (the pound sign followed immediately by a plus sign).

Normally, the global parameters are specified at the beginning of the /etc/brutab file. Global brutab parameters can also be set as environment variables. These environment variables will override the settings in the /etc/brutab file. To remove any of these environment variables use the unset PARAMETER command i.e. unset BRURAW.

Here is a list of global brutab parameters (with default values), showing how they are specified:

#+ ZBUFSIZE=500k

These parameters are explained in greater detail:

This variable points to your command shell. This shell is used when BRU spawns a task for running other tasks (such as switching tapes in a loader.)

BRU will check the tape (by reading the first block) before attempting to do a backup. BRU will read the date of the tape before proceeding. BRU will then compare the date in the archive header of the tape to the number of days specified in the RECYCLEDAYS filed. If the tape is newer then the number of days specified by RECYCLEDAYS field BRU will prompt you for a different tape. NOTE: This parameter only take effect for devices that have been specified and defined in the /etc/brutab file. They have no effect for other devices.

The values specified by RECYCLEDAYS field is read by BRU and compared to the tape. Here’s an example: Assume that you are doing today’s backup and accidentally try to use the backup tape from yesterday. If RECYCLEDAYS=7 is set, then BRU will give you a warning and refuse to overwrite yesterday’s tape. To continue, you will need to use a blank tape or a BRU tape more than a week old. You should set RECYCLEDAYS to a value that is consistent with your tape rotation schedule.

You can disable date checking by setting RECYCLEDAYS=0. However, this will not completely disable OVERWRITEPROTECT. BRU will still do a “tape change” check on multi-volume archives. NOTE: This parameter only take effect for devices that have been specified and defined in the /etc/brutab file. They have no effect for other devices.

The MAXWRITES option works in conjunction with the OVERWRITEPROTECT option and allows you to limit the number of times a specific piece of media (tape) can be used before it is recommended for removal from tape rotation. If this value is exceeded, BRU will issue a warning and refuse to continue.
Below you will find a few recommendations for various tape types. Although some of these settings might seem low compared to the manufactures specifications we feel that a more conservative value will insure the integrity of your data.

4MM/8MM DAT 200
AIT 1/2/3/4 500
VXA-1/2 500
DLT 1000
SDLT 1000
SAIT 1000
LTO 10000

Setting MAXWRITES=0 will disable checking of the number of writes. NOTE: This parameter only take effect for devices that have been specified and defined in the /etc/brutab file. They have no effect for other devices. The RECYCLEDAYS and MAXWRITES parameters have no effect unless OVERWRITEPROTECT is specified.

If BRUTABONLY is specified as a global parameter, BRU will permit only the use of devices listed in the /etc/brutab file. If the user attempts to use a device that is not listed, BRU will issue a warning message and refuse to continue until the correct device is specified.

DEVNAMECHECK causes BRU to perform a “sanity check” on the device name to prevent the creation of a large file in the /dev directory. If BRUTABONLY is YES, then this option is inactive.

MATCHLEVEL determines the level of pathnames matching performed by BRU during a backup or restore. A level of 0 will only match the exact pathname entered (i.e.: /tmp/123 will not match ./tmp/123 or tmp/123, only /tmp/123 will match). A level of 1 will match relative pathnames that indicate the same path (i.e.: tmp/123 will match itself and ./tmp/123, but /tmp/123 will not match). Level 3 will match any similar pathname (i.e.: tmp/123 will match /tmp/123, tmp/123 and ./tmp/123). NOTE: This setting can cause some confusion, be aware of what your MATCHLEVEL is set to when doing restores. By default we have set this option to two (2) to allow maximum flexibility when restoring. This is covered in more detail in Chapter 17, “Extracting Files: The BRU Restore Function”

This option allows you to transfer BRU archive files from a UNIX system that supports long file names (greater than 14 characters) to a system with short file names. If you set MAXFILENAMELEN to the maximum length your system will support, it causes files with longer names to be renamed (not truncated). A warning message is issued for each renamed file. The default setting for MAXFILENAMELEN is the maximum file name length your system supports. On certain versions of UNIX (usually older ones), MAXFILENAMELEN defaults to 14. On newer OS’s (like Solaris and Linux), it is set to 1023 or more.

On many NFS mounted volumes, it isn’t possible for BRU to easily determine if a file is locked. To prevent excessive read errors or a possible hang condition, BRU will pre-read files to check for a lock state. A 0 means no pre-read, a 1 means pre-read only files that appear to be locked and a 2 means to pre-read ALL files (which can slow your backup performance).

If most of your files are small, (less than a megabyte in size), then a setting of ZBUFSIZE=500K (or smaller) would probably work well. If you have many large database files (greater than 10 megabytes), then a setting of ZBUFSIZE=5M (or larger) might work better. For example, if BRU compresses a 500K byte file by 50%, then it would need 250K bytes to store the compressed data in its compression buffer. To compress a 2-megabyte file by 50%, 1 megabyte would be needed, etc. NOTE: Setting ZBUFSIZE to a large value may cause BRU to fail. This is not a problem with BRU but is due to limits on the amount of memory that can be allocated to a UNIX process. You may be able to increase the maximum available process memory by adjusting your UNIX kernel parameters but this is not recommended unless you are familiar with “kernel-tuning” and know what you’re doing.

This variable points to the location and name of the BRU readme or helpfile. By default the location of that file is /bru/bruhelp.

This variable sets the maximum number of warning that BRU will report before aborting the current operation. By default this is set to 1000.

This is the variable that sets the maximum number of errors that BRU will report before aborting the current operation. By default this is set to 500.

BRUXPAT=/Library/Application Support/ArGest Backup/etc/bruxpat
This variable sets the location of the bru exclusion file. Paths and files listed in this file will be excluded from the backup or restore if the -QX option is placed in the bru command line, refer to Chapter 15, “File Inclusion and Exclusion.” By default the file location and name is /Library/Application Support/ArGest Backup/etc/bruxpat.

This variable sets the location of the file containing descriptions of raw data partitions to be backed up or restored by BRU. By default, this files location is /etc/bruraw. This file and the commands used with bru to activate this file are in Chapter 5, “Archive Creation” later in this manual. This used in conjunction with the -r option.

BRUSMARTREST=/Library/Application Support/ArGest Backup/etc/brusmartrest
This variable sets the name and location of the BRUSMARTREST file. Files listed in this file will be handled as open and restored using a protected method, alleviating the problem of restoring over an open file or shared library. By default this file is located in 
/Library/Application Support/ArGest Backup/etc/brusmartrest.

This variable sets the location and name of the results of the SmartRestore. In the event that a restored file’s “text busy” flag was set, we rename the original file and then restore the appropriate file. As a result, we create a Bourne shell script that will clean up the old, renamed files. If you are creating scripts to run BRU, it is a good idea to execute this file as the last stage of any restore that is preformed. By default this file is located in 

MOUNTCMD=”(null)” /bin/mountcmd
This parameter allows the user to specify external commands to handle devices. MOUNTCMD is used to specify a command that will be called before BRU attempts to open a device for reading or writing. NOTE: If you set this option with a environment variable and want to “unset” it, then use the following command “unset MOUNTCMD” (under the Bourne shell).

UNMOUNTCMD=”(null)” /bin/unmountcmd
The UNMOUNTCMD should be used to specify a command that will be called after BRU has finished reading/writing. NOTE: If you set this option with a environment variable and want to “unset” it, then the following command “unset UNMOUNTCMD” (under the Bourne shell). The MOUNTCMD and UNMOUNTCMD parameters were designed for use with multiple-cartridge tape handlers (stackers or jukeboxes). BRU passes four arguments to the commands specified by MOUNTCMD and UNMOUNTCMD.

Argument Description
1 device name (i.e. ntape0)
2 volume number (i.e. 2)
3 mode letter (i.e. ‘c’ or ‘x’)
4 media size in Kilobytes (i.e. 150000)

In most cases, the commands specified will be shell scripts. Normally, these scripts issue commands that will cause a tape handler to load or unload a tape. See Appendix K, “Using MOUNTCMD and UNMOUNTCMD,” for samples of shell scripts that use these commands.

With this option your backups are backwardly compatible with older versions of BRU prior to 14.2.

This option toggles BRU’s ability to write a Label for each Volume in a multi-volume backup. By default BRU will create a label on each volume during its backup process.

NOTE: For Technical Support Use Only. Please leave these settings unchanged.