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Chapter 4. Indexing with Amanda

Alan M. McIvor

Original text

Stefan G. Weichinger

XML-conversion;Updates
AMANDA Core Team

Table of Contents

Database Format
Database Browsing
File Extraction
Protocol Between amindexd and amrecover
Installation Notes
Permissions
Changes from amindex-1.0
Changes from amindex-0.3
Changes from amindex-0.2
Changes from amindex-0.1
Changes/additions to 2.3.0
Known Bugs

Note

Refer to http://www.amanda.org/docs/indexing.html for the current version of this document.

This file describes how the index files are generated and how amrecover is used.

Database Format

The database consists of a directory tree of the format: $host/$disk/$date_$level.gz

The host and disk are those listed in the disklist file, the "$host/$disk/" is like the curinfo database, '/' are changed for '_'. There is an index file for each dump, the name of the file is made of the date and the level, they will have the .gz suffix if they are compressed with gzip.

ex. The file foo/_usr/19991231_0.gz is the index of the level 0 made on 19991231 of the disk /usr of the host foo.

The files are ASCII text files containing a list of the directory and files of the dump, one per line. Each entry is the filename relative to the mount point, starting with a /, e.g., /home/user1/data from the disk mounted on /home would generate the entry /user1/data. The index files are stored in compressed format (eg gzip or compress).

Database Browsing

The client is called amrecover and is loosely based on the functionality of the program recover from Backup Copilot. A user starts up amrecover. This requires specifying the index server and the Amanda config name (defaults for both are compiled in as part of the installation). Then the user has to specify the name of the host information is wanted about, the disk name, and (optionally) the disk mount point. Finally a date needs to be specified. Given all this, the user can then roam around a virtual file system using ls and cd much like in a FTP client. The file system contains all files backed up on the specified date, or before that date, back to the last level 0 backup. Only the most recent version of any file is shown.

As the file system is traversed, the user can add and delete files to a "shopping list", and print the list out.

File Extraction

When a user has built up a list of files to extract, they can be extracted by issuing the command extract within amrecover.

Files are extracted by the following, for each different tape needed.

As part of the installation, a "tape server" daemon amidxtaped is installed on one or more designated hosts, which have an attached tape drive. This is used to read the tapes. See the config files for the options for specifying a default.

amrecover contacts amidxtaped on the tape server host specifying which tape device to use, which host and disk files are needed for. On the tape server host, amidxtaped executes amrestore to get the dump image file off the tape, and returns the data to amrecover.

If dumps are stored compressed for the client, then amrecover pipes the data through the appropriate uncompression routine to uncompress it before piping it into restore, which then extracts the required files from the dump image.

Note that a user can only extract files from a host running the same operating system as he/she is executing amrecover on, since the native dump/restore tools are used - unless GNU-tar is used.

Protocol Between amindexd and amrecover

The protocol talked between amindexd and amrecover is a simple ASCII chat protocol based on that used in FTP. amrecover sends a 1 line command, and amindexd replies with a 1 line or multi-line reply. Each line of the reply starts with a three digit code, starting with a '5' if an error occurred. For 1 line replies, and the last line of a multi-line reply, the 4th character is a space. For all but the last line of a multi-line reply, the 4th character is a '-'.

The commands and replies other than acknowledgments are:

Table 4.1. Protocol between amindexd and amrecover

QUITfinish up and close connection
HOST <host>set host to host
DISK <disk>set disk to disk
LISTDISK [<device>]list the disks for the current host
SCNF <config>set Amanda configuration to config
DATE <date>set date to date
DHSTreturn dump history of current disk
OISD <dir>Opaque is directory? query. Is the directory dir present in the backups of the current disk back to and including the last level 0 dump.
OLSD <dir>Opaque list directory. Give all filenames present in dir in the backups of the current disk back to and including the last level 0 dump.
ORLD <dir>Opaque recursive list directory. Give all filenames present in dir and subdir in the backups of the current disk back to and including the last level 0 dump.
TAPEreturn value of tapedev from amanda.conf if set.
DCMPreturns "YES" if dumps for disk are compressed, "NO" if dumps aren't.

Installation Notes

  1. Whether or not an index is created for a disk is controlled by a disk configuration option index. So, in amanda.conf you need to define a disktype with this option, e.g.,

    define dumptype comp-user-index {
    comment "Non-root partitions on reasonably fast machines"
    compress client fast
    index yes
    priority medium
    }
    
  2. You need to define disks that you want to generate an index for to

    be of one of the disktypes you defined which contain the index option. This cause sendbackup-dump on the client machine to generate an index file which is stored local to the client, for later recovery by amgetidx (which is called by amdump).

  3. Amanda saves all the index files under a directory specified by

    "indexdir" in amanda.conf. You need to create this directory by hand. It needs to have read/write permissions set for the user you defined to run Amanda.

    If you are using the "text database" option you may set indexdir and infofile to be the same directory.

  4. The index browser, amrecover, currently gets installed as part of the client software. Its location may not be appropriate for your system and you may need to move it to a more accessible place such as /usr/local/bin. See its man page for how to use it.

    Note that amindexd, amgetidx, amidxtaped, and amtrmidx all write debug files on the server in /tmp (unless this feature is disabled in the source code), which are useful for diagnosing problems. amrecover writes a debug file in /tmp on the machine it is invoked.

Permissions

The userid chosen to run the Amanda client code must have permission to run restore since this is used by createindex-dump to generate the index files.

For a user to be able to restore files from within amrecover, that user must have permission to run restore.

Changes from amindex-1.0

Get index directory from amanda.conf.

Integration into Amanda-2.3.0.4.

Rewriting of amgetidx to use amandad instead of using rsh/rcp.

Changes from amindex-0.3

Support for index generation using GNU-tar.

Support for restoring files from within amrecover.

Bug fixes:

  • index/client/amrecover.c (guess_disk): Removed inclusion of mntent.h and use of MAXMNTSTR since this was non-portable, as pointed out by Izzy Ergas .

  • index/client/display_commands.c (list_directory): Removed point where list_directory() could sleep for ever waiting for input that wasn't going to come.

  • index/server/amindexd.c index/client/uscan.l Installed patches from Les Gondor to make amrecover handle spaces in file names.

  • server-src/amcontrol.sh: As pointed out by Neal Becker there were still a few sh-style comments that needed conversion to c-style.

Changes from amindex-0.2

  • index/client/Makefile.in

  • index/client/help.c

  • index/client/amrecover.h

  • index/client/uparse.y

  • index/client/uscan.l Added a help command.

  • index/client/set_commands.c: set_disk() and set_host() now check for empty extract list.

  • index/client/extract_list.c:

  • index/client/amrecover.h:

  • index/client/uparse.y:

  • index/client/uscan.l: Added clear extract list command.

  • index/client/set_commands.c (set_disk): Added code so working directory set to mount point.

  • index/client/extract_list.c: If the last item on a tape list is deleted, the tape list itself is now deleted from the extract list.

  • index/client/amrecover.c:

  • index/server/amindex.c: If the server started up and found that the index dir doesn't exist, then it exited immediately and the client got informative message. Corrected this so it is obvious what is wrong to the user, since this is most likely to occur when somebody is setting up for the first time and needs all the help they can get.

  • server-src/amcontrol.sh

  • server-src/Makefile.in Amcontrol is now parameterized like other scripts and run through munge to generate installable version.

  • index/server/amindexd.c (main): Added code to set userid if FORCE_USERID set.

  • index/server/amindexd.c Removed #define for full path of grep. Assumed now to be on path.

  • client-src/createindex-dump.c

  • client-src/sendbackup-dump.c

  • man/Makefile.in Added patch from Philippe Charnier so they work when things are installed with version numbers. This was also reported by Neal Becker . Also patch to set installed man page modes and create directory if needed.

  • config/options.h-sunos4 Corrected definition for flex library.

  • server-src/amtrmidx.c Added some pclose() commands, used remove() instead of system("rm .."). Problems reported by Pete Geenhuizen () on a system with small ulimits set.

  • index/server/amindexd.[ch]

  • index/server/list_dir.c

  • index/client/amrecover.c

  • index/client/set_commands.c

  • index/client/uparse.y Changes developed with the help of Pete Geenhuizen to support disks specified by logical names. Also, now debug files generated by amrecover include PID so multiple users can use amrecover simultaneously and without file deletion permission problems.

  • config/config.h-hpux:

  • config/config-common.h:

  • server-src/amgetidx.c: Changes from Neal Becker re remote shell, making it a configuration parameter.

  • config/options.h-sunos4 Had -Lfl instead of -lfl

Changes from amindex-0.1

  • index/client/uscan.l: added support for abbreviated date specs

  • index/client/amrecover.c (guess_disk): guess_disk got disk_path wrong if mount point other than / (as subsequently pointed out by Eir Doutreleau )

  • server-src/amtrmidx: Added amtrmidx which removes old index files.

  • index/client: Added a pwd command

  • server-src/amgetidx.c (main): Added use of CLIENT_LOGIN username on r commands. (as pointed out by Eric Payan )

  • server-src/amgetidx.c: Bug: It was copying from all clients irrespective of whether the client was configured for indices. A '}' in the wrong place.

  • server-src/amgetidx.c: Removed user configuration section. Instead include amindexd.h to get information.

Changes/additions to 2.3.0

common-src/conffile.[ch]

  • added "index" as a valid option

server-src/driverio.c

  • added code to optionstr() to write "index" into option string

client-src/sendback-dump.c

  • added code to generate index if requested.

client-src/indexfilename.[ch] client-src/createindex-dump.c

  • code to generate index.

client-src/Makefile.in

  • a new target. Another file for sendbackup-dump

config/config-common.h

  • added def of restore.

Known Bugs

  • Empty directories don't get into the listing for a dump (at all dump levels).

  • When amrecover starts up, it tries to guess the disk and mount point from the current directory of the working system. This doesn't work for disks specified by logical names, nor when an automounter is being used, or a link is in the path.