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dump/restore of a fs with 100 of millions hardlinks
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RESTORE(8) BSD System Manager's Manual RESTORE(8) NAME
restore -- restore files or file systems from backups made with dump SYNOPSIS
restore -i [-chmvy] [-b blocksize] [-f file] [-s fileno] restore -R [-cvy] [-b blocksize] [-f file] [-s fileno] restore -r [-cvy] [-b blocksize] [-f file] [-s fileno] restore -t [-chvy] [-b blocksize] [-f file] [-s fileno] [file ...] restore -x [-chmvy] [-b blocksize] [-f file] [-s fileno] [file ...] (The 4.3BSD option syntax is implemented for backward compatibility, but is not documented here.) DESCRIPTION
The restore command performs the inverse function of dump(8). A full backup of a file system may be restored and subsequent incremental backups layered on top of it. Single files and directory subtrees may be restored from full or partial backups. Restore works across a net- work; to do this see the -f flag described below. Other arguments to the command are file or directory names specifying the files that are to be restored. Unless the -h flag is specified (see below), the appearance of a directory name refers to the files and (recursively) subdi- rectories of that directory. Exactly one of the following flags is required: -i This mode allows interactive restoration of files from a dump. After reading in the directory information from the dump, restore provides a shell like interface that allows the user to move around the directory tree selecting files to be extracted. The avail- able commands are given below; for those commands that require an argument, the default is the current directory. add [arg] The current directory or specified argument is added to the list of files to be extracted. If a directory is specified, then it and all its descendents are added to the extraction list (unless the -h flag is specified on the command line). Files that are on the extraction list are prepended with a ``*'' when they are listed by ls. cd arg Change the current working directory to the specified argument. delete [arg] The current directory or specified argument is deleted from the list of files to be extracted. If a directory is speci- fied, then it and all its descendents are deleted from the extraction list (unless the -h flag is specified on the com- mand line). The most expedient way to extract most of the files from a directory is to add the directory to the extrac- tion list and then delete those files that are not needed. extract All the files that are on the extraction list are extracted from the dump. Restore will ask which volume the user wishes to mount. The fastest way to extract a few files is to start with the last volume, and work towards the first volume. help List a summary of the available commands. ls [arg] List the current or specified directory. Entries that are directories are appended with a ``/''. Entries that have been marked for extraction are prepended with a ``*''. If the verbose flag is set the inode number of each entry is also listed. pwd Print the full pathname of the current working directory. quit Restore immediately exits, even if the extraction list is not empty. setmodes All the directories that have been added to the extraction list have their owner, modes, and times set; nothing is extracted from the dump. This is useful for cleaning up after a restore has been prematurely aborted. verbose The sense of the -v flag is toggled. When set, the verbose flag causes the ls command to list the inode numbers of all entries. It also causes restore to print out information about each file as it is extracted. -R Restore requests a particular tape of a multi volume set on which to restart a full restore (see the -r flag below). This is useful if the restore has been interrupted. -r Restore (rebuild a file system). The target file system should be made pristine with newfs(8), mounted and the user cd'd into the pristine file system before starting the restoration of the initial level 0 backup. If the level 0 restores successfully, the -r flag may be used to restore any necessary incremental backups on top of the level 0. The -r flag precludes an interactive file extraction and can be detrimental to one's health if not used carefully (not to mention the disk). An example: newfs /dev/rrp0g eagle mount /dev/rp0g /mnt cd /mnt restore rf /dev/rst8 Note that restore leaves a file restoresymtable in the root directory to pass information between incremental restore passes. This file should be removed when the last incremental has been restored. Restore, in conjunction with newfs(8) and dump(8), may be used to modify file system parameters such as size or block size. -t The names of the specified files are listed if they occur on the backup. If no file argument is given, then the root directory is listed, which results in the entire content of the backup being listed, unless the -h flag has been specified. Note that the -t flag replaces the function of the old dumpdir(8) program. -x The named files are read from the given media. If a named file matches a directory whose contents are on the backup and the -h flag is not specified, the directory is recursively extracted. The owner, modification time, and mode are restored (if possible). If no file argument is given, then the root directory is extracted, which results in the entire content of the backup being extracted, unless the -h flag has been specified. The following additional options may be specified: -b blocksize The number of kilobytes per dump record. If the -b option is not specified, restore tries to determine the block size dynamically. -c Normally, restore will try to determine dynamically whether the dump was made from an old (pre-4.4) or new format file system. The -c flag disables this check, and only allows reading a dump in the old format. -f file Read the backup from file; file may be a special device file like /dev/rmt12 (a tape drive), /dev/rsd1c (a disk drive), an ordinary file, or '-' (the standard input). If the name of the file is of the form ``host:file'', or ``user@host:file'', restore reads from the named file on the remote host using rmt(8). -h Extract the actual directory, rather than the files that it references. This prevents hierarchical restoration of complete subtrees from the dump. -m Extract by inode numbers rather than by file name. This is useful if only a few files are being extracted, and one wants to avoid regenerating the complete pathname to the file. -s fileno Read from the specified fileno on a multi-file tape. File numbering starts at 1. -v Normally restore does its work silently. The -v (verbose) flag causes it to type the name of each file it treats preceded by its file type. -y Do not ask the user whether to abort the restore in the event of an error. Always try to skip over the bad block(s) and continue. DIAGNOSTICS
Complaints if it gets a read error. If -y has been specified, or the user responds 'y', restore will attempt to continue the restore. If a backup was made using more than one tape volume, restore will notify the user when it is time to mount the next volume. If the -x or -i flag has been specified, restore will also ask which volume the user wishes to mount. The fastest way to extract a few files is to start with the last volume, and work towards the first volume. There are numerous consistency checks that can be listed by restore. Most checks are self-explanatory or can ``never happen''. Common errors are given below. Converting to new file system format. A dump tape created from the old file system has been loaded. It is automatically converted to the new file system format. <filename>: not found on tape The specified file name was listed in the tape directory, but was not found on the tape. This is caused by tape read errors while looking for the file, and from using a dump tape created on an active file system. expected next file <inumber>, got <inumber> A file that was not listed in the directory showed up. This can occur when using a dump created on an active file system. Incremental dump too low When doing incremental restore, a dump that was written before the previous incremental dump, or that has too low an incremental level has been loaded. Incremental dump too high When doing incremental restore, a dump that does not begin its coverage where the previous incremental dump left off, or that has too high an incremental level has been loaded. Tape read error while restoring <filename> Tape read error while skipping over inode <inumber> Tape read error while trying to resynchronize A tape (or other media) read error has occurred. If a file name is specified, then its contents are probably partially wrong. If an inode is being skipped or the tape is trying to resynchronize, then no extracted files have been corrupted, though files may not be found on the tape. resync restore, skipped <num> blocks After a dump read error, restore may have to resynchronize itself. This message lists the number of blocks that were skipped over. FILES
/dev/rmt? the default tape drive /tmp/rstdir* file containing directories on the tape. /tmp/rstmode* owner, mode, and time stamps for directories. ./restoresymtable information passed between incremental restores. SEE ALSO
dump(8), newfs(8), mount(8), mkfs(8), rmt(8) BUGS
Restore can get confused when doing incremental restores from dumps that were made on active file systems. A level zero dump must be done after a full restore. Because restore runs in user code, it has no control over inode allocation; thus a full dump must be done to get a new set of directories reflecting the new inode numbering, even though the contents of the files is unchanged. HISTORY
The restore command appeared in 4.2BSD. 4th Berkeley Distribution May 1, 1995 4th Berkeley Distribution
