Backup3G/User Guide/Appendix A - Installing and Configuring

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Appendix A—Installing and Configuring backup3G is installed through the COSmanager configuration menu. This appendix describes how to install and configure backup3G for your environment. COS/Stacker is an add-on module that provides interface routines for jukebox control under backup3G. For details on installing, configuring, and using COS/Stacker, see the COS/Stacker User Guide. See Installing COSmanager Applications in the COSmanager User Guide for full details of how to install COSmanager applications and modules. What you need • the COSmanager framework installed on the target platform • a distribution tape containing backup3G • a valid license key • you must be a COSmanager user with the Manager or Config role 144 Appendix A—Installing and Configuring Installing backup3G 1. First, load the distribution tape in a drive on the local host or a network drive. 2. From the Product configuration menu, select COSmanager configuration > COSmanager applications. 3. Select Application > Install. 4. Enter the name of the host to which the tape drive is attached. In Install from, enter the no-rewind device name for the tape drive. Press Accept. 5. You will see a list of the applications on the tape. Choose the row titled ‘backup3G version 3.2’. 6. Enter the name of the directory where you want backup3G to be installed and press Accept. The install procedure now: • adds an entry for backup3G 3.2 to the COSmanager applications table • copies the backup3G files from the tape to the target directory • creates local directories under $FShome/backup_3.2 • creates symbolic links for the FS backup drivers • creates the backup3G audit trail directory backlog in the system spool area. This completes the installation phase. You should now exit COSmanager before configuring backup3G. When you restart COSmanager, the button bar and COSmanager configuration menu will be rebuilt to include the backup3G options. Appendix A—Installing and Configuring 145 Configuring backup3G The next step is to set up backup3G for your environment, by running some or all of the initial configuration tasks. Some of these configuration tasks supply information that is required by backup3G. Other tasks are optional, and extend the basic information in backup3G to include information about your organization’s procedures and computing environment. You can run or rerun these tasks at any time. Note We recommend that you review your backup policies and procedures before starting configuration. See Planning Your Backup Policies and Procedures on page 20. Running backup3G initial configuration tasks 1. GUI mode: Select Config from the COSmanager button bar. CUI mode: Select Product configuration from the COSmanager main menu. 2. Select backup3G configuration > Initial configuration. COSmanager shows the list of configuration tasks. Figure 39 — Initial configuration tasks 146 Appendix A—Installing and Configuring 3. To start configuration, select Perform > All outstanding from the menu bar. Note In CUI mode, the menu bar is accessible from the function key assigned to the Menu button—usually F8. For each task you will see a screen offering a number of options, like this: Figure 40 — Example of an outstanding configuration task Press Exit to stop the configuration procedure. You can continue the configuration later by selecting Initial configuration from the backup3G configuration menu. Press Skip to skip to the next outstanding task. Note that some duties later in the configuration require earlier duties to have been run. Press Accept to execute this task now. 4. Work through each task in turn. The following topics contain some useful information on each task, or a pointer to a detailed description elsewhere in the manual. Appendix A—Installing and Configuring 147 Removable Media Drives This defines a list of available backup drives and drive pools. A backup drive is one that will be used by backup or recovery jobs running on the current host to read or write data. This includes both drives physically connected to this host, and drives accessible via the network. Any drives that will be used to write to or read media must be defined to backup3G. Auto-loading devices such as tape stackers and jukeboxes should be defined as media locations. Drives that are accessible but which will not be used for backup and recovery don’t need to be defined to backup3G. For more information see How To Add A New Tape or Disk Drive on page 136. Before you begin To define a Removable Media Drive you will need to have set up details of: • all hosts on the network that have a backup drive attached to them. This was probably done when COSmanager was configured. The procedure is described in the COSmanager User Guide, in the chapter Configuring COSmanager. If you need to add a host location now you can do it from this task, through Maintain > Location. • all media types that will be used for backup. backup3G has a table of standard media types, so you only need to add new or uncommon media types that you use for backup or archive. You can add media types now, through Maintain > Media type. For more information, see Adding a New Media Type on page 124. • all locations from which media are loaded into backup drives, whether short-term (tape stacker, computer-room trolley) or longer-term (jukebox, media library). You can add media and load locations from this task, through Maintain > Location. For more information, see Adding a New Media Location on page 116. 148 Appendix A—Installing and Configuring Add Media to the Media Library This task allows you to add details of new media batches to the database. You can also add details of locations where media are stored, and add a new media type. Media management policies and procedures This is a good time to review your current media management procedures, to see if you could be using media in a more secure or efficient way. You should consider the following: • your strategies for routine backup and data recovery (media types, label types, retention periods) • your media maintenance strategy (media usage types, maintenance procedures) • where media can be stored and for how long (media locations). Before you begin Before you can add backup media, you will need to have set up details of: • all media types that you use for backup • all locations where media are stored or used. These should already have been set up in the previous configuration task, Removable Media Drives, but you can still add them now if necessary. To add a media type now, use Maintain > Media type (see Adding a New Media Type on page 124). To add a media location, use Maintain > Location (see Adding a New Media Location on page 116). To add a batch of backup media 1. Select Maintain > Add batch from the ‘Media Details’ window. The fields are described in detail in To add a media batch on page 118. Appendix A—Installing and Configuring 149 Generate Simple Backup Scheme This task generates a simple weekly schedule of backup jobs to perform full and incremental backups of your main filesystems. For many sites this scheme will be all that is required. Larger organizations can build on this framework by adding other backup jobs. The task steps through each mountable filesystem and asks which day of the week a full backup is to be performed. All other filesystems are set up to be incremental backups for that day. Before you begin You must have defined all your backup drives. See Removable Media Drives on page 147. backup3G includes several standard retention periods. If you wish to use a different period you must set it up in advance. See To define a retention period on page 88. Steps 1. backup3G explains what this task is about to do. Press Generate to continue. 2. Choose the backup format (cpio is recommended). This can easily be changed later. 3. Choose the backup drive to use for daily backups. 4. Choose the retention period for each backup. As the backup scheme works to a weekly cycle we recommend that you use a retention period of at least one or two weeks. 5. For each mountable filesystem on this host a confirm screen will display, asking you on which day the full backup is to be run. 150 Appendix A—Installing and Configuring Figure 41 — Choose which day to run the full backup Press the button corresponding to the day of the week. Unless another filesystem is also chosen for this day all other filesystem backups are assumed to be incremental. If you don’t want to generate a backup scheme for this filesystem, press Skip. 6. Once all filesystems have been dealt with, a backup job is generated for each working day of the week. The job for each day is displayed, showing one job step for each full and incremental filesystem backup. Appendix A—Installing and Configuring 151 Figure 42 — Daily backups generated by ‘simple backup scheme’ Press Print to print a listing of the generated backups for your records. Press Exit when you are finished. You may wish to customize the generated filesystem backup jobs and backup items. Examples: change the default scheduled time from 23:00; add in the offsite storage location; add or remove backup steps; add new backup jobs to cater for non-filesystem backups. See the major topics in the chapter Setting Up Backups, in particular: • How to Define a Backup Job on page 78 • How to Define a Backup Item on page 74. 152 Appendix A—Installing and Configuring Create Symbolic Links for Methods Run by FSremote If one or more remote backup hosts are running COS/Manager version 2.7 or earlier, you must create symbolic links to certain backup3G programs so that they can be accessed from ~COSmanager/bin. If you do not have any such remote hosts, there is no need for these symbolic links. Steps 1. Press Accept to create the symbolic links, or press Exit to skip this task. Figure 43 — Symbolic links created for FSremote methods Appendix A—Installing and Configuring 153 Add backup3G Duties to duty3G If you also have the duty3G application, you can add a batch of duties relating to backup3G. duty3G features more advanced options for scheduling backups, and provides a simpler interface for users who only need access to a few backup3G functions. If duty3G is already installed, you can add the backup3G duties now. If you install duty3G in future, you can run this task afterwards to add the backup3G duties. The extra duties take up less than 1 KB of disk space. Steps 1. Press Accept to add the backup duties to the duty table, or press Skip to skip this task. 154 Appendix A—Installing and Configuring Install/Deinstall Enterprise Backup Support backup3G can back up machines running Windows NT, Windows 3.1/95, or Net- Ware. This task installs special backup, recovery, and communications methods on the UNIX host to support these non-UNIX hosts. Figure 44 — Install/deinstall enterprise backup clients Steps If you don’t need to install any enterprise backup clients, press Exit. 1. If you do wish to install some or all of the enterprise backup clients, Press Choose to select them. 2. Set Action to ‘install’. Press Accept to install the backup clients. Appendix B—Checking Job Status Codes 155 Appendix B—Checking Job Status Codes To check the status of all backup jobs on a host: 1. Log in to the host and start backup3G 2. Select Monitor (GUI version) or Monitor backup jobs & maintain logfiles (CUI version). The Backup Monitor is a dynamic display showing the status of all scheduled and running backups, and all completed backups that have not yet been acknowledged. To help diagnose a problem you can get more information by highlighting the backup then selecting Logfiles > Display. This appendix lists suggested actions to be taken for each status code. Note Your operating system or drives may return other status codes not known to backup3G. 156 Appendix B—Checking Job Status Codes Status of Active Backup and Recovery Jobs This table lists status codes for jobs that are currently active—that is, they have been scheduled or started but not yet completed. Table 8 — Status codes for active backup and recovery jobs Status Meaning Action Scd: <time> The job is scheduled to start at <time> None Waiting for drive The job is queued and is waiting for a drive to become available. None Run: PID #M Step #N The job currently running step #N of a multipart backup. None Attn: Change media (drive is manually-loaded) The job is waiting for an operator to load the next scratch volume. Unload the volume that was just written and load a new scratch volume. (From the Backup Monitor: Jobs > Change volume). Attn: Change media (drive has an auto-loading device) The job can’t find a valid scratch volume in the stacker/jukebox. Allocate more scratch volumes to the stacker/jukebox location. (From the Stacker option: Maintain > Media > Move > Alloc scratch). Attn: Load #volume (drive is manually-loaded) A recovery job is waiting for an operator to load the next backup volume. Load the requested backup volume. (From the Backup Monitor: Jobs > Change volume). Attn: Load #volume (drive has an auto-loading device) A recovery job can’t find the volume containing the next file(s) to be recovered in the stacker/jukebox. Load the requested volume into the stacker/jukebox. (From the Stacker option: Maintain > Media > Move > Alloc active). Appendix B—Checking Job Status Codes 157 Status of Completed Backup and Recovery Jobs. Table 9 — Status codes for completed backup and recovery jobs Status Meaning Action Cancelled The job was cancelled by an operator before it started. Check why the job was cancelled. End: Killed The job was cancelled by an operator while it was running. Check why the job was killed. End: Successful The job completed without errors. None End: Status 1-2 Backup command failed, probably due to a usage error. Check the backup log for other error messages. Use ‘Show steps’ to check that the command run by this backup step is correct. If you filled in the Options field for this backup item, check that the options are recognized by the backup command. End: Status 80 ‘Device open’ error. Check that the drive is online, clean, and operating correctly. End: Status 81 The media change failed. Add new volumes of this media type, or scratch some existing backup volumes. End: Status 82 Child process killed—no child exit status. Probably means that the process running the backup method was killed by a user from the command line. Check why the process was killed and rerun the backup job. End: Status 83 Not enough data read into input buffer. Probably indicates a system problem—can’t be fixed within backup3G. End: Status 90 Error reading data from or writing to device. Usually indicates unexpected endof- tape or media error. Check the tape. If writing a backup, try another volume. If recovering data from a backup, try another drive. End: Status 91—94 Various other device I/O errors. Check the drive. End: Status 95—98 Various stdio I/O errors. May indicate a system problem—possibly low swap space. End: Status 99 Job failed or was cancelled by an operator, e.g. during volume change. Check the backup log for other error messages.

Appendix C—Backup Methods and Drivers 159 Appendix C—Backup Methods and Drivers A backup method is the ‘how to’ of a backup step. It contains the command(s) that will write the backup data. backup3G comes with a number of standard backup methods and driver scripts. These scripts use standard UNIX utilities to provide a uniform set of facilities for backing up and recovering files across a network. In effect the drivers ‘top up’ the basic facilities provided by cpio, dump, and tar. This appendix describes: • how multi-part backup methods work • how to customize the behavior of backup methods by passing optional arguments from a backup item • features of the driver scripts supplied with backup3G. Appendix D—Defining Backup Methods describes how to create a new backup method. 160 Appendix C—Backup Methods and Drivers Multi-part Backup Methods: How They Work The recommended method for multi-part backup of filesystems and lists of files and directories is ‘full cpio - MP’. The recommended backup method for multi-part backup of raw partitions and large files is ‘image copy - MP’. Multi-part backup methods based on FSmcpio call a program FSbusplit to split the backup. FSbusplit uses the size of the file or filesystem and the part size and capacity of the backup medium to calculate how many parts and volumes to split the backup over. FSbusplit uses an algorithm that tries to minimize the number of partitions needed. By default, FSmcpio can back up files larger than the part size but smaller than the capacity of the volume. FSmcpio simply writes the file to a single larger than usual part. Files larger than the volume’s capacity are rejected with a warning message. To reject files larger than the part size, specify the -B flag to FSmcpio in the Options field of the backup item. The multi-part methods automatically issue a “change media” request after writing the last part on each volume. The method used to change volumes depends on the logical drive definition. If the last partition on the previous volume was incomplete it is rewritten in full at the start of the new volume. Although it isn’t mandatory, it is best if multi-part backup steps start writing at the beginning of a volume (backup3G assumes this when it does its capacity calculations). If the multi-part step starts half-way through a volume, it’s likely to write up to the physical end-of-volume, and so the last part will have to be restarted on the next volume. To sum up, if a multi-part step is not the first in a job to write data, you should insert a ‘change media’ backup step before it to force backup3G to start writing at the start of a new volume. Each of the multi-part backup methods has a corresponding ‘single-part’ method. For example: ‘full cpio’ writes a backup step in cpio format to a single tape file or part. ‘full cpio - MP’ writes a backup step in cpio format, if necessary in more than one part or over more than one volume. Appendix C—Backup Methods and Drivers 161 We recommend that you use a multi-part backup method where possible, particularly where the directory being backed up: • won’t fit on a single volume • is growing, and may not fit in future • is very large, and you want to speed recovery of selected files by splitting the backup into several parts. For backups that are guaranteed not to exceed the capacity of a single volume, the advantage of the single-part methods is that they will start up marginally faster. Capacity and Part Size You can tune the Multi-part size and Capacity parameters for a media type to make your backups run more efficiently. The following principles should be used as a guide. • Capacity should be slightly less than the theoretical maximum capacity of the media type, to allow for the label and for variations in the actual tape length among different vendors. A rule-of-thumb is to subtract about 2%. • Multi-part size should be larger than the size of the largest file. • One part cannot span volumes, so Multi-part size must not be larger than the capacity of the volume. • It should be small enough so that the time taken to read or write a part is fairly small (say less than 10 minutes). • Small parts are more efficient if the data are compressed, either by hardware compression or by use of a compressed backup method. See Data Compression on page 41. • Large parts are faster for recovering a full filesystem but slower for recovering selected files. If the Multi-part size field is left blank, then the Capacity field will be used in its place. That is, each volume will contain one whole partition. If both Capacity and Multi-part size are defined, backup3G calculates how many partitions can fit on the output volume, and requests a media change after it has written the last full partition or if an I/O error (End of Media) occurs. 162 Appendix C—Backup Methods and Drivers If Capacity is not defined, it defaults to unlimited capacity. This means that partitions will be written to the volume until an I/O error occurs. backup3G assumes this means that end-of-volume has been reached, though it could also be due to some other cause such as a physical defect on the tape. Caution By default, FSmcpio will back up a file larger than the part size. However, if Capacity is null, the partitioning algorithm can’t reject files larger than the real capacity of the volume. The backup step will keep requesting a new volume, trying to write the file in full, until it runs out of scratch volumes or is cancelled. To avoid this, either exclude such files from the backup; set a realistic value for capacity; or specify the -B flag in the Options field. Appendix C—Backup Methods and Drivers 163 Passing Options to a Backup Method Each backup item includes an Options field, with which you can pass optional flags and arguments to the backup command as command line parameters. For example, the cpio backup methods supplied with backup3G accept several flags that change the way backups are done. Some of these can be specified through fields in the backup item. One example is the Index field. This passes the -I flag that instructs FScpio to create an online index. Other flags have no field set aside for them in the ‘Backup item’ prompt form. Some examples: See FScpio(1) for a full list of flags. Example: exclude unwanted files from backup You have a backup item to backup the filesystem /user2 on host mama using the backup method ‘full cpio - MP’. You want to exclude core and object files and certain temporary files of the form tmpxxxx. To exclude these files from the backup, you would: 1. Select Maintain backup jobs from the backup3G configuration menu. 2. Select Items > Maintain. 3. Select the backup item from the list displayed. 4. Select Maintain > Change. -s <files> back up this list of files -x <files> exclude from the backup this list of files -d perform a deleting backup -z use the alternate index method ls_index 164 Appendix C—Backup Methods and Drivers Figure 45 — Passing arguments to the backup method 5. In the Options field, enter -x "*/*.o */core */tmp*" These options will be appended to the cpio command at run time. Note backup3G does not validate any of the options when you create or change the backup item. If any of the options are unrecognized or the syntax is incorrect, the backup step will fail when the backup job tries to execute the command. You can specify more than one flag. The only limit is the length of the Options field. If you have added your own backup methods to the set provided with backup3G, use Options to take advantage of any flags and features that are recognized by your backup command but aren’t built in to the backup item prompt form. List of files to be excluded from the backup Appendix C—Backup Methods and Drivers 165 backup3G Driver Scripts backup3G includes several backup drivers. These drivers use the standard utilities cpio, dump, and tar, and provide a uniform set of facilities to backup and recover files across a network and to create online indexes. In effect the drivers ‘top up’ the basic facilities provided by cpio, dump, and tar to a common level. Another driver, FSimage, performs an image copy of a raw disk partition or very large file. Table 10 shows what features are supported by each driver. Refer to the manual page for more information. Generally we recommend that you use a backup method based on FSmcpio. For particular uses other drivers may be more suitable. See below for notes on working with particular FS backup drivers. Table 10 — Attributes of FS backup drivers Create Index Driver Data Format When the Backup is Created? From an Existing Backup? Remote Backup? Multi-part Backup? Include/ Exclude Selected Files FScpio cpio 4 4 4 4 FSmcpio cpio 4 4 4 4 4 FSimage imagea a. writes a 1 KB header followed by a byte-by-byte copy of the data. 4 FSmimage image 4 4 FSdump dumpb b.dump is not available under AIX or SCO. 4c c. FSdump uses the ls_index method to create the index when the backup first starts. 4 FStar tar 4 4 4 FSfilesys filesystemd d. copies the specified files/directories to another directory using cpio -p. 4 4 4 166 Appendix C—Backup Methods and Drivers FScpio FScpio can’t back up a read-only filesystem FScpio is not suitable for backing up a read-only filesystem. There are two problems. First, cpio will not be able to reset the access times of the files. Second, the .FSbackup file cannot be created as FScpio cannot write to the filesystem. To back up a read-only filesystem you should use a different backup method, one not based on FScpio. Backing up symbolic links with FScpio The FScpio -y flag allows backup of data pointed to by symbolic links, whereas normally only the links themselves are backed up. FScpio uses find(1) to gather the list of files to be backed up. The -y flag tells find to follow symbolic links. Note that if the file being pointed to is in another filesystem, you must also use the -m flag (‘cross mount points’) to allow FScpio to back up the file. Appendix C—Backup Methods and Drivers 167 FSdump FSdump backup methods and online indexes backup3G generates an online index by extracting directory information about the files being backed up, using options on the underlying backup command. For example, both cpio and tar have flags -tv that list file details. The backup drivers FScpio and FStar use these flags (with a little help from sed) to generate output similar to that produced by ls -l. However, the BSD dump command doesn’t have any options to produce equivalent file information. FSdump gets around this by doing an ls command just before the backup. However, there are a few points you should be aware of: • the filesystem must be mounted to do an index; dump permits backup of an unmounted filesystem, but the ls command will fail • the index can only be created at the same time as the original backup. FScpio and FStar can extract file information later from the backup volume; FSdump cannot. This also means that you cannot verify a dump format backup by creating an index from the backup volume, as you can with other methods • because the ls is done before the dump starts, the index may not be completely accurate if the filesystem is active during the backup. For example, if a file is changed after FSdump creates the index but before the file is backed up, the backup itself will be correct but the index will show the modification time, permissions, owner and file size as they were before the file was edited. If this is a problem, the safest method is to mount the filesystem as readonly before running the backup, then re-mount it as read-write afterwards. Alternatively, you can define backup methods that will perform the mounts. 168 Appendix C—Backup Methods and Drivers FSimage Recovering a disk partition using FSimage Note that there can be a potential problem on some systems when restoring an image backup: If the size of the disk partition is not a multiple of the tape block size, some tape drives will pad out the incomplete last block. When the partition is restored the last block is written in full back to disk. The result is that the restored partition is larger than the original. Most operating systems handle this correctly, but success cannot be guaranteed for all tape drives and all systems. The image copy methods based on FSimage can write a 1 KB header. This is used in the recovery to ensure that the file, when recovered, has exactly the same size, owner, group, and permissions. backup3G writes the header by default; we recommend that you accept this behavior to avoid the padding problem. If you choose not to have backup3G write a header, another solution is to make sure that the size of the disk partition is a multiple of the tape block size. For example, with a 200 MB disk partition (204,800 KB), possible tape block sizes are: Block size No. of blocks 32 KB 6400 Correct 20 KB 10240 Correct 27 KB 7585.2 INCORRECT Appendix D—Defining Backup Methods 169 Appendix D—Defining Backup Methods If you wish to keep using your own backup software or a third-party product, you can define the commands as a new backup method. This appendix describes how to define a new backup method, and lists the variables maintained by backup3G that you can use to customize how a backup method works. 170 Appendix D—Defining Backup Methods How to Define Backup Methods Each step in a backup job names a data object and the method that will be used to back it up. A method can also implement a related step that doesn’t write data. Any command or script that could be run from the UNIX prompt can be used in a backup method. backup3G maintains several variables that you can use in a backup command—see Shell Variables in Backup Commands on page 174. Here is the definition of one common method, ‘full cpio’. FScpio is a driver (supplied with backup3G) which writes the data in cpio format. The flags -f and -I mean that a full backup is to be done and an online index will be created. ‘full cpio’ is a convenient and descriptive way to refer to this command for use with many different backup jobs. If the command format or site requirements ever change, only the method needs to be changed in one place. Every backup job that uses that method will automatically be updated. Note The FS backup drivers provide a consistent front-end to the underlying archiving commands. They do not write data in a proprietary format. For example, FScpio uses the standard cpio command and writes data in standard cpio format. To define a backup method 1. Select backup3G configuration > Maintain tables 2. Select the ‘Backup Method’ table, then select Table > Maintain to see the backup methods that have already been defined. 3. Select Maintain > Add, and enter the following fields: Format cpio Backup Command FScpio -f -I \"$Indexfile\" $Directory Description Full backup of directory using cpio Appendix D—Defining Backup Methods 171 Figure 46 — Adding a backup method Backup method Enter a descriptive name. Include some attributes of the method, such as the name of the command or format, whether it will do full or incremental backups, and whether it supports multi-part backups. Example: incr cpio - MP Description Ideally this is an expansion of the method name. This description will help other users when choosing a backup method from the list of available methods. Format Select a backup format. This determines the recovery method. Leave Format blank if you are defining a non-backup method (a method that doesn’t write data). Backup command Enter the command that you want this method to execute. Note Any double-quotes (") in the backup command must be protected by a backslash character, that is \". If this is not done the command will be incorrectly parsed by the shell. 172 Appendix D—Defining Backup Methods If you left the Format field blank, the next four fields are set to default values. If you selected a backup format, the information in these three fields helps backup3G to process the backup command. Multipart support? Select ‘yes’ if your method supports multipart backups. (See $APPL_HOME/bin/FSmcpio for an example of how to implement support for multi-part backups and online indexes.) Uses STDOUT?Select ‘yes’ if your backup command writes to standard output (stdout). Select ‘no’ if it writes directly to the device. If you select ‘yes’, backup3G uses devio(1) to read stdout and write the data to the device, using the block size specified for this media type in the media table. Index support? Select ‘yes’ if your method supports online indexes. Generally this will be ‘yes’ if you use one of the standard backup drivers (FScpio, FSfilesys, FSdump or FStar), otherwise ‘no’. Remote support? Select ‘yes’ if your method supports backup and recovery on a remote host. This doesn’t mean that all backups using your method must be run remotely. It just tells backup3G to give users the option when defining a backup. If Uses STDOUT? is ‘yes’, the method automatically supports remote backup. Run on host Governs on which host the method will run. For remote backups, select ‘drive-host’ if the method only accesses the backup drive without writing data, otherwise use ‘file-host’. Select Accept to save the changes and return to the methods table. Example: defining a backup method Define a method ‘xback full’ to do a full backup using xback, which is a script that you have written to back up a whole directory in dump format. xback does not Appendix D—Defining Backup Methods 173 support online indexes. The command is entered in the format: xback <dirname> 1. Select the ‘Backup Method’ table from backup3G configuration > Maintain tables, then select Table > Maintain to list the backup methods, then Select Maintain > Add. Backup method Enter the name ‘xback full’. Description Enter a description. Format Select ‘dump’ format. Backup command Enter xback $Directory. Multipart support? Select ‘no’. Uses STDOUT?Assume xback writes to standard output, and select ‘yes’. Index support? Select ‘no’. Remote support? As xback uses stdout, Remote support? is ‘yes’. Run on host ‘xback full’ supports remote backup and writes data; it will automatically run on the same host as the files. Select Accept to save the changes and return to the methods table. You will now be able to select ‘xback full’ when defining a new backup item. 174 Appendix D—Defining Backup Methods Shell Variables in Backup Commands Table 11 lists the variables maintained by backup3G that you can refer to in your backup command. All the variables that are data amounts (Blocksize, Capacity, and Part_size) are in kilobytes (KB). The syntax for referring to variables is similar to shell syntax: $<variablename>. Note You can use the fields status and maxstatus for dependency tests. Variable Description maxstatus The highest exit status of the backup steps run so far. status The exit status from the previous backup step. Blocksize The block size of the backup volume. Capacity The data storage capacity of the backup volume. Comments Comments from the backup item relating to current backup step. Days The number of days to retain the backup volume. Density The density of the backup volume. Device The rewind-on-close device file for the backup drive. Device_nr The ‘no rewind-on-close’ device file for the backup drive. Directory The directory which is to be backed up. Drive The logical backup drive name. Drivehost The host to which the backup drive is connected. Drivename The physical backup drive name. Appendix D—Defining Backup Methods 175 Table 11 — Variables available to be used in backup commands File The file number on volume being written or about to be written. Format The format in which the backup is written. Host The host on which the data lives (the file host). Indexfile The file name for the online index. NULL means ‘do not generate an index’. Item The backup item number referred to by the current backup step. Job Backup job name. Length The length of the backup volume. Method The backup method used by the backup item. Mode The backup job mode (scheduled, automatic or at-request). Number The media number of the volume currently being written to. Part_size The maximum size of each part in a multi-part backup. Pool Group of logical drives Queuename Name of the physical drive or drive pool to which the job is queued. Once the job starts running, Queuename = Drivename Retention The retention period for the backup media. Seq The sequence number of this volume in the media set produced by this job. Step Backup step number. Time The time of day that the backup was scheduled to run. Type The backup media type.