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Test Your Knowledge in Computers #36
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Moving processes from the main memory of a memory-constrained Linux computer to disk is called 'swapping'.
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bup-midx(1) [debian man page]

bup-midx(1)						      General Commands Manual						       bup-midx(1)

NAME
bup-midx - create a multi-index (.midx) file from several .idx files SYNOPSIS
bup midx [-o outfile] <-a|-f|idxnames...> DESCRIPTION
bup midx creates a multi-index (.midx) file from one or more git pack index (.idx) files. Note: you should no longer need to run this command by hand. It gets run automatically by bup-save(1) and similar commands. OPTIONS
-o, --output=filename.midx use the given output filename for the .midx file. Default is auto-generated. -a, --auto automatically generate new .midx files for any .idx files where it would be appropriate. -f, --force force generation of a single new .midx file containing all your This will result in the fastest backup performance, but may take a long time to run. --dir=packdir specify the directory containing the .idx/.midx files to work with. The default is $BUP_DIR/objects/pack and $BUP_DIR/indexcache/*. --max-files maximum number of .idx files to open at a time. You can use this if you have an especially small number of file descriptors avail- able, so that midx can complete (though possibly non-optimally) even if it can't open all your .idx files at once. The default value of this option should be fine for most people. --check validate a .midx file by ensuring that all objects in its contained .idx files exist inside the .midx. May be useful for debugging. EXAMPLE
$ bup midx -a Merging 21 indexes (2278559 objects). Table size: 524288 (17 bits) Reading indexes: 100.00% (2278559/2278559), done. midx-b66d7c9afc4396187218f2936a87b865cf342672.midx DISCUSSION
By default, bup uses git-formatted pack files, which consist of a pack file (containing objects) and an idx file (containing a sorted list of object names and their offsets in the .pack file). Normal idx files are convenient because it means you can use git(1) to access your backup datasets. However, idx files can get slow when you have a lot of very large packs (which git typically doesn't have, but bup often does). bup .midx files consist of a single sorted list of all the objects contained in all the .pack files it references. This list can be binary searched in about log2(m) steps, where m is the total number of objects. To further speed up the search, midx files also have a variable-sized fanout table that reduces the first n steps of the binary search. With the help of this fanout table, bup can narrow down which page of the midx file a given object id would be in (if it exists) with a single lookup. Thus, typical searches will only need to swap in two pages: one for the fanout table, and one for the object id. midx files are most useful when creating new backups, since searching for a nonexistent object in the repository necessarily requires searching through all the index files to ensure that it does not exist. (Searching for objects that do exist can be optimized; for exam- ple, consecutive objects are often stored in the same pack, so we can search that one first using an MRU algorithm.) SEE ALSO
bup-save(1), bup-margin(1), bup-memtest(1) BUP
Part of the bup(1) suite. AUTHORS
Avery Pennarun <apenwarr@gmail.com>. Bup unknown- bup-midx(1)

Check Out this Related Man Page

bup-tag(1)						      General Commands Manual							bup-tag(1)

NAME
bup-tag - tag a commit in the bup repository SYNOPSIS
bup tag bup tag <tag name> <committish> bup tag -d <tag name> DESCRIPTION
bup tag lists, creates or deletes a tag in the bup repository. A tag is an easy way to retreive a specific commit. It can be used to mark a specific backup for easier retrieval later. When called without any arguments, the command lists all tags that can be found in the repository. When called with a tag name and a com- mit ID or ref name, it creates a new tag with the given name, if it doesn't already exist, that points to the commit given in the second argument. When called with '-d' and a tag name, it removes the given tag, if it exists. bup exposes the contents of backups with current tags, via any command that lists or shows backups. They can be found under the /.tag directory. For example, the 'ftp' command will show the tag named 'tag1' under /.tag/tag1. Tags are also exposed under the branches from which they can be reached. For example, if you create a tag named 'important' under branch 'computerX', you will also be able to retrieve the contents of the backup that was tagged under /computerX/important. This is done as a convenience, and should the branch 'computerX' be deleted, the contents of the tagged backup will be available through /.tag/important as long as the tag is not deleted. OPTIONS
-d, --delete delete a tag EXAMPLE
$ bup tag new-puppet-version hostx-backup $ bup tag new-puppet-version $ bup ftp "ls /.tag/new-puppet-version" files.. $ bup tag -d new-puppet-version SEE ALSO
bup-save(1), bup-split(1), bup-ftp(1), bup-fuse(1), bup-web(1) BUP
Part of the bup(1) suite. AUTHORS
Gabriel Filion <lelutin@gmail.com>. Bup unknown- bup-tag(1)

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