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dump(8) System Manager's Manual dump(8) NAME dump, rdump - Performs incremental file system dumps SYNOPSIS /usr/sbin/dump [key [argument ...] file system] /usr/sbin/rdump -f dump_file [otherkey [argument ...] file system] rdump DESCRIPTION The dump command copies to the default /dev/rmt0h, or to the alternate storage device specified with the -f flag, all files and any associated extended attributes changed after a certain date in the specified local file system. The rdump command copies to the dump_file storage device all files and any associated extended attributes changed after a certain date in the specified file system. These commands cannot be used to archive AdvFS filesets. See for the operations used to archive AdvFS filesets. The dump and rdump commands are used to dump local files and any asso- ciated local attributes from a single file system defined by the file system parameter to a local or remote storage device, respectively, where file system contains the files you want to back up. The dump and rdump commands perform similar functions with respect to storage of files contained in the named file system. However, the rdump command requires that the -f flag be used with any otherkey and the special dump_file parameters. Both commands copy all files in file system whose dump level is less than a specified value, and that have changed after a specified date to the default storage device or to an alternate storage device. The dump level and date are specified in the local /etc/dumpdates file. The key and argument parameters specify one or more options that may be used to write files to the storage medium. Characters permitted by the key pa- rameter are similar to flags that consist of any of the characters 0123456789bcdfnsuwBNSTW only, which may be used in any logical combina- tion, but must be preceded with the - (dash) character; the argument parameter specifies other options that tell these dump and rdump processes what to do. These options are described in the FLAGS sec- tion. Not all keys permit argument options to be specified. The /etc/dumpdates file consists of 3-column record lines that specify the file system name, a dump level, and a standard time-stamp. These processes enter a time-stamp into the file system record after each file in the named file system is successfully backed up. The 3-column record in the /etc/dumpdates file contains the following information: Lists the file system device name. This is an integer between 1 and 9 that defines a hierarchy for files in file system. This hierarchy in- dicates which files should be written to the storage medium when the dump or rdump command is executed. Level 0 defines all the files in file system. When a level is assigned, all files equal to and less than that level in file system are backed up. The time-stamp tells the dump or rdump process when file system had its last backup. This time- stamp is written by the dump or rdump process after the specified file system backup is completed. When there is no time-stamp, the dump or rdump process assumes the beginning of time (called the Epoch). The /etc/dumpdates file is written in ASCII and consists of a single record per line. This file may be edited to change any record field, when necessary. Either process requires operator intervention when any of the following conditions occur: end-of-tape, end-of-dump, tape-write error, tape-open error, or when the number of disk-read errors is greater than 32. In addition to alerting all operators specified by the -n key, these processes interact with an operator at the terminal from which dump or rdump was invoked when either program can no longer proceed. All queries written to standard output by the dump or rdump process must be answered by typing yes or no on the invoking terminal. Because a dump to any storage medium requires excessive time to process, each process checks itself at the start of each storage vol- ume. In many instances, the default dump performance can be improved by modifying the number of blocks per write. For additional informa- tion, see the description for the -b switch in the FLAGS section. When a volume write fails, dump or rdump restarts itself from the last successful checkpoint, with operator permission, after the currently written storage medium is properly removed and another (replacement) storage medium has been mounted. These processes also tell an operator what is going on at periodic in- tervals when writing to the storage medium. This information consists of somewhat conservative estimates for the number of blocks to write, the number of storage media that must be used for the dump, the time to complete the dump, and the time until the storage medium must be re- placed with another one to complete the dump. Output is verbose, so that others know that the terminal controlling dump is busy. When pro- cessing takes place, the following conditions apply: Fewer than 32 read errors during a dump or rdump tape-dump process are ignored. Each renewal of the storage medium requires a new dump process, so that parent processes for storage media already written are in effect until the entire storage medium is written. When the dump command has the W or w key set, no records are written to the standard output for a file system that has no current record in the /etc/dump- dates file, even when listed in the /etc/fstab file. When no argument is specified, the key parameter is assumed to be -9u so that the de- fault file system is dumped to a default storage medium named /dev/rmt0h (usually a tape). dump The dump command copies to the default /dev/rmt0h, or to the alternate storage device specified with the -f flag, all files changed after a certain date in the specified local file system. rdump The rdump command copies to the dump_file storage device all files changed after a certain date in the specified file system. This command is similar in operation to dump, except that the -f flag is always specified (see the FLAGS section) together with any otherkey you may wish to specify. The dump_file parameter should always be specified by machine name and device name as machine:device name. The rdump command starts remote server /usr/sbin/rmt or /etc/rmt on the client machine to access the storage medium. Another vendor's rdump command may fail because rmt is not located in /etc. To avoid this problem, it may be necessary to provide a symbolic link on the machine pointing to /usr/sbin/rmt, as shown in the follow- ing example: ln -s /usr/sbin/rmt /etc/rmt Although the rdump command can detect magnetic tape on remote ULTRIX and DIGITAL UNIX systems, it cannot detect magnetic tape on other re- mote systems. Instead, it defaults to treating the output medium as a disk file and aborts the operation should it encounter overflow or I/O error cases. Remote systems must be able to run the uname command if you are to use the rdump command. If a remote system cannot run the uname command, you can set the environment variable OSF_RDUMP_SIMP_RCMD before you at- tempt the operation. EXIT VALUES The dump and rdump commands exit with 0 status on success. Startup er- rors are indicated with an exit code of 1; abnormal termination is in- dicated with an exit code of 3. FLAGS Specifies the dump level. All files modified since the last time-stamp whose names are currently stored in the /etc/dumpdates file for a named file system at levels less than the one specified are dumped to tape. When no time-stamp entry is defined for a dump level, the Epoch is as- sumed; thus, the value -0 for this key causes the entire file system to be dumped to the storage medium. Specifies the number of blocks in 1024 bytes to write to the storage medium. The default write block value is 10 blocks (or 10 kilobytes). In many instances, increasing the number of blocks per write will increase your dump performance. For optimal results on Digital's platform, use a value that is greater than or equal to 32, is a multiple of 4, and is less than 65. The dump medium is a not a 9-track cartridge tape. Specifies the write density of the storage medium. The density parameter is expressed in bits per inch (bpi). This information is used in calculating the amount of medium used per each volume of the storage medium. For the dump com- mand, the density will be automatically provided by Digital base system supported devices. Otherwise, the default write density for the dump and rdump commands is 1600 bpi. Writes the dump to the dump_file stor- age device instead of the default tape drive. When the name of dump_file is - (dash), the dump process writes to standard output. When the name of the dump_file is /dev/nrmt*, the dump process will enable the -N flag. When the rdump command is invoked, the dump_file parameter must specify both the remote machine and the storage device in the format ma- chine:device, where machine is the name or reference designation of the host machine and device is the name or reference designation of the storage device. Specifies the label of the dump to be displayed during restoration. The default label is "No Label". The label can be a max- imum of 16 characters. Notifies, by means of a command similar to wall(1), all operators in the group named operator, which is specified in the /etc/group file whenever dump or rdump requires operator atten- tion (to change a tape, for example). Specifies the size of a dump tape. The size parameter is expressed in feet. When the amount of tape specified by size has been written, either process waits for the current reel to be changed (see the -n flag). For the dump command, the tape size will be automatically provided by Digital base system sup- ported devices. Otherwise, the default tape size for the dump and rdump commands is 2300 feet. Writes the time of the beginning of the dump as the time-stamp entry in the /etc/dumpdates file for the file system record when the dump successfully completes. Tells an operator what file systems must be dumped to the storage device. This informa- tion is obtained from the /etc/dumpdates and /etc/fstab files. The -w key tells either process to print to the standard output a record for each file system listed in the /etc/dumpdates file. Specifies a block- mode device. For the dump command, the estimated calculations will be based on the device's storage capacity instead of density and size. Prints the estimated size of the dump file in 1-kilobyte blocks and the estimated number of volumes that make up the dump file, only. The dump file will be opened and closed, but nothing will be written to it. The information will be output through standard error and will have a for- mat like the following: 23382 blocks, 0.04 volumes If the dump file is on disk, the format will be: 23382 blocks The parameter placement will be preserved, but the exact words "blocks," and "volumes" are not guaranteed. Refer to the EXAMPLES sec- tion for further information. Disables the rewinding of the tape and placing the tape unit off line after completing the dump session. By default, when the dump command finishes backing up a file system it rewinds the tape and takes it off line. For some tape subsystems, this tape will be ejected from the unit. The -N flag is the default when the dump_file parameter is /dev/nrmt*. If you use the -N flag to dump to a regular file that does not have the letters "rm" in its name, dump will inform you of your error in using -N and terminate. Specifies output file size in feet. When the -B flag is used, the full_tape_size parameter specifies the output file size in number of 1024-byte blocks. Specifies a tape number, which is used in the dialog with the operator as the number of the first tape. Prevents any extended attributes from being archived with associated files. Similar to -w, but for any file system listed in the /etc/dump- dates file, prints an output record and highlights this record with the > (greater than) character, all files that must be dumped. When -W is specified, all other options are ignored and dump exits immediately. NOTES Estimates for dump and rdump. The information in this note is specific to Digital tape devices and the densities and sizes they use under rdump. The size and density information is used to estimate the number of volumes required for the current dump or rdump request. Some of the factors that will effect the estimate calculation include the following: Track format Compression Interrecord gap size Writing optimization technologies Appending to a tape The estimate calculation does not take these factors into ac- count and can result in very large (100-500%) miscalculations. The estimates can be customized by adjusting the size in feet (-s) or size in 1024-byte block (-BS) variables to the desired results. The default values for /dev/rmt*h devices used in the dump estimate calculation are shown in the following table: tab(@); lfHB cfHB cfHB cfHB c c c c l r r r . _ Tape Device@Density@Size@Size @(bpi)@(feet)@(1024-byte blocks) _ TA78@6250@1925@141056 TA79@6250@1925@141056 TA81@6250@1925@141056 TA90@38000@436@194560 TA91@38000@436@194560 TF30@6667@1182@92416 TF70@10000@2457@287948 TF70L@10000@2457@287948 TK50@6667@1182@92416 TK70@10000@2457@287948 TKZ09@54000@7456@4718592 TLZ04@61000@1584@1132646 TLZ06@61000@2640@1887436 TLZ07@61000@2640@1887436 TS05@1600@2075@38912 TU77@1600@2075@38912 TU78@1600@2075@38912 TU80@1600@2075@38912 TU81@1600@2075@38912 TU81E@1600@2075@38912 TZ05@1600@2075@38912 TZ07@1600@2075@38912 TZ30@6667@1182@92416 TZ85@42500@4925@2453299 TZ857@42500@4925@2453299 TZK08@54000@3276@2073600 TZK10@16000@2580@483840 _ The rdump command starts the remote server /usr/sbin/rmt on the client machine to access the storage medium. If the rdump com- mand cannot find /usr/sbin/rmt, it will try /etc/rmt and rmt. The rdump program can detect remote tape support on DIGITAL UNIX and ULTRIX systems. However, due to the lack of a standard for UNIX magnetic tape functions, it cannot utilize remote tape sup- port on other systems. This means that multivolume dumpsets can only be created when the remote system is DIGITAL UNIX, DEC OSF/1 (the former name of DIGITAL UNIX), or ULTRIX, or if there is embedded multivolume support in the remote system (such as is the case with VMS, where support is in the Magtape ACP). For rare cases where the remote system is non-UNIX, compatibility may require that rdump not use UNIX-like commands. In order to obtain this behavior, the user or system manager should use the following command: setenv OSF_RDUMP_SIMP_RCMD The previous command can be used on a system wide (global) or per rdump command basis. For proper operation, the server's /.rhosts file must contain the name or reference designation of the client's machine. The rdump and the dump commands do not handle MFS or AdvFS filesystems. After encountering tape write errors, dump or rdump queries the operator about performing a rewrite. If the operator requests a rewrite, a rewind is per- formed, followed by an attempt to rewrite the data. In the event the no-rewind device is used, the user should always load a new tape to avoid the possibility of overwriting previously written archives. EXAMPLES To perform a full level 0 dump, enter a command similar to the follow- ing: dump -0un -f /dev/rmt1h -b 32 /fs1 In this example, 0 specifies that all files in the file system fs1 will be dumped to /dev/rmt1h; u specifies dump to update the /etc/dumpdates file after a successful dump of the file system; and n specifies that operators will be notified. The estimate calculation will be based upon the tape device defaults. The write block size is set to 32 kilobytes. To dump a local file system to a remote storage tape, enter a command similar to the following: rdump -3u -f tape_server:/dev/rmt1h /fs1 In this example, 3 specifies the dump level of all files in the file system /fs1 that will be dumped to tape /dev/rmt1h on sys- tem tape_server, and u specifies the dump to update the /etc/dumpdates file after a successful dump of the file system. The estimated calculation will be based on the rdump defaults. The write block size will be the default. To obtain an esti- mated number of blocks and volumes for the current dump session, enter the following: dump -0Ef /dev/rmt1h /usr The system dis- plays output similar to the following: 358696 blocks, 0.19 vol- umes The following examples show alternative ways of scheduling backups. Select the backup schedule that best fits your needs. 7-day incremental schedule The following schedule is a 7-day incremental schedule. This schedule is useful for small-to-medium storage systems. The ba- sic algorithm is n, n+1, ... The number of dump files to per- form a full restore can vary from 1 to 7. The following is an example of a 28-day schedule: 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7-day alternative differential schedule The following schedule is a 7-day alternative differential schedule. This schedule is useful for small-to-medium storage systems. The basic algorithm is n-1, n+3, ... The number of dump files to perform a full restore can vary from 1 to 4. The following is an example of a 28-day schedule: 0 5 4 7 6 9 8 0 5 4 7 6 9 8 0 5 4 7 6 9 8 0 5 4 7 6 9 8 28-day alternative differential schedule The following schedule is a 28-day alternative differential schedule. This schedule is useful for small-to-large storage systems. The algorithm combines the 7-day incremental and the 7-day alternative differential schedules. The number of dump files to perform a full restore can vary from 1 to 7. The fol- lowing is an example of a 28-day schedule: 0 5 4 7 6 9 8 1 5 4 7 6 9 8 2 5 4 7 6 9 8 3 5 4 7 6 9 8 This schedule limits full dumps to once a month. Therefore, it is possible to lose a month's worth of data. Alternative approaches to address this problem might include duplicating the full tape or doing full backups twice a month instead of once a month. FILES The dump command path in single user mode. The dump command path in multiuser mode. Used by the rdump remote tape access program. Con- tains a list of file systems that were backed up, the date that each file system was backed up, and the backup level. RELATED INFORMATION Commands: restore(8), rrestore(8), rmt(8) delim off dump(8)