# NAME git-annex sim - simulate a network of repositories # SYNOPSIS git annex sim start [my.sim] git annex sim step N git annex sim command git annex sim end # DESCRIPTION This command simulates the behavior of git-annex in a network of repositories, recording which files would reach which repositories according to the configuration of preferred content, numcopies, trust level, etc. The input to the simulation is the configuration contained in the repository it is run in, supplimented with an optional sim file, which can be used to add repositories, change configuration, etc. The simulation writes to an output sim file as it runs, which contains the entire simulation input, as well as the results of the simulation. This allows re-running the same simulation later, as well as analyzing the results of the simulation. While a simulation is running, the git-annex branch of the current repository is updated along the way with the simulated repositories and the simulated locations of files. Additional annexed files can also be staged in the index. This allows using any git-annex command, such as `git-annex whereis` to examine the state of the simulation. git-annex will refuse to merge the simulated git-annex branch with other non-simulated git-annex branches, to avoid the simulation leaking out into the real world. Ending the simulation returns the git-annex branch to its original state, and undoes any staged changes to the index. Note that the reflog will still contain the simulated states of the git-annex branch, which will increase the size of the git repository for some time before git eventually garbage collects them. The simulation can be run for a number of steps with eg `git-annex sim step 10`. On each step, a simulated repository is selected, and an action is performed in it. The actions include pushing and pulling the git-annex branch to and from remotes of the simulated repository, and simulating the transfer of annexed files to and from remotes according to the configuration. The configuration of the simulation can be changed while it is running by using the usual git-annex commands, eg "git-annex numcopies 3" as well as by using "git annex sim [command]" to run a command in the same format used in the sim file. Configuration changes take effect in the next step of the simulation, and are recorded in the output sim file. # THE SIM FILE This text file is used to configure the simulation and also to report on the results of the simulation. Each line takes the form of a command followed by parameters to the command. Lines starting with "#" are comments. Here is an example sim file: # add repositories to the simulation and connect them as remotes init foo init bar connect foo <-> bar # add a special remote initremote baz connect foo -> baz <- bar # configure repositories numcopies 2 group foo client wanted foo standard group bar archive wanted bar standard wanted baz include=*.mp3 # add annexed files in the working tree to the simulation, as if they # were just added to repository foo addtree foo include=*.mp3 addtree foo include=*.jpg addtree foo include=bigfiles/ # add simulated annexed files add bigfile 100gb bar add hugefile 10tb foo # run the simulation forward by ten steps step 10 # remove foo's remote bar and see if a new file added to foo reaches bar disconnect foo -> bar add foo foo.mp3 2mb step 5 # SIM COMMANDS This is the full set of commands that can be used in the sim file as well as passed to "git annex sim" while a simulation is running. * `init name` Initialize a simulated repository, giving it a name that will be used in the simulation. * `initremote name` Initialize a simulated special remote. * `use name here|remote|description|uuid` Use an existing repository in the simulation, with its existing configuration. The repository is given a name for the purposes of the simulation. The repository to use can be specified by remote name, uuid, etc. Example: "use myrepo here" * `connect repo [<-|->|<->] repo [...]` Add a connection between two or more repositories. The arrow indicates which direction the connection runs, and it can be bidirectional. For example, "connect foo -> bar" makes bar be a remote of foo, while "connect foo <-> bar" makes each be the remote of the other. A chain of connections can extend to many repositories, eg "connect foo -> bar -> baz -> foo" * `disconnect repo [<-|->|<->] repo [...]` Removes connections between repositories. For example, "disconnect foo -> bar" makes foo no longer have bar as a remote. * `addtree repo expression` Adds annexed files from the git repository to the simulation making them be present in the specified repository. The expression is a preferred content expression (see [[git-annex-preferred-content]](1)) specifying which annexed files to add. While it is possible to include all or a large number of files this way, note that often it's more efficient to simulate a small quantity of files that have the particular properties you are interested in. This can be used with the same files more than once, to make multiple repositories in the simulation contain the same files. * `add filename size repo [repo ...]` Create a simulated annexed file with the specified filename and size, that is present in the specified repository, or repositories. The size can be specified using any usual units, eg "10mb" or "3.3terabytes" The filename cannot contain a space. This stages a file in the index, so that regular git-annex commands can be used to query the state of the simulated annexed file. If there is already an annexed file by that name, it will be overwritten with the new file. Note that the simulation does not cover adding conflicting files to different repositories. The files in the simulation are the same across all simulated repositories. * `step N` Run the simulation forward by this many steps. * `seed N` Sets the random seed to a given number. Using this should make the results of the simulation deterministic. The output sim file always has the random seed included in it, so usually you don't need to specify this. * `present repo file` This indicates the expected state of the simulation at this point. The repository should contain the content of the file. If it does not, the discrepancy will be indicated on standard error, and the `git-annex sim` command will eventually exit nonzero. This is added to the output sim file as the simulation runs. * `notpresent repo file` This indicates the expected state of the simulation at this point. The repository should not contain the content of the file. If it does, the discrepancy will be indicated on standard error, and the `git-annex sim` command will eventually exit nonzero. This is added to the output sim file as the simulation runs. * `numcopies N` Sets the desired number of copies. This is equivilant to [[git-annex-numcopies]](1). * `group repo group` Add a repository to a group. This is equivilant to [[git-annex-group]](1). * `ungroup repo group` Remove a repository from a group. This is equivilant to [[git-annex-ungroup]](1). * `wanted repo expression` Configure the preferred content of a repository. This is equivilant to [[git-annex-wanted]](1). * `required repo expression` Configure the required content of a repository. This is equivilant to [[git-annex-required]](1). * `groupwanted group expression` Configure the groupwanted expression. This is equivilant to [[git-annex-groupwanted]](1). * `maxsize repo size` Configure the maximum size of a repository. This is equivilant to [[git-annex-maxsize]](1). * `rebalance [on|off]` Setting "rebalance on" is the equivilant of passing the --rebalance option to git-annex. Setting "rebalance off" undoes that. For example: maxsize foo 1tb rebalance on step 100 rebalance off # OPTIONS * The [[git-annex-common-options]](1) can be used. # HASKELL INTERFACE There is also a Haskell interface to the simulation, in the git-annex source tree in the Annex.Sim module. This allows implementing simulations in pure Haskell code, without the overhead of using a git repository. # SEE ALSO [[git-annex]](1) [[git-annex-test]](1) # AUTHOR Joey Hess Warning: Automatically converted into a man page by mdwn2man. Edit with care.