Before jumping into the broader topic of repository administration, let's further define what a repository is. How does it look? How does it feel? Does it take its tea hot or iced, sweetened, and with lemon? As an administrator, you'll be expected to understand the composition of a repository both from a literal, OS-level perspective—how a repository looks and acts with respect to non-Subversion tools—and from a logical perspective—dealing with how data is represented inside the repository.
Seen through the eyes of a typical file browser application (such as Windows Explorer) or command-line based filesystem navigation tools, the Subversion repository is just another directory full of stuff. There are some subdirectories with human-readable configuration files in them, some subdirectories with some not-so-human-readable data files, and so on. As in other areas of the Subversion design, modularity is given high regard, and hierarchical organization is preferred to cluttered chaos. So a shallow glance into a typical repository from a nuts-and-bolts perspective is sufficient to reveal the basic components of the repository:
$ ls repos conf/ db/ format hooks/ locks/ README.txt
Here's a quick fly-by overview of what exactly you're seeing in this directory listing. (Don't get bogged down in the terminology—detailed coverage of these components exists elsewhere in this and other chapters.)
- conf/
This directory is a container for configuration files.
- db/
This directory contains the data store for all of your versioned data.[49]
- format
This file describes the repository's internal organizational scheme. (As it turns out, the
db/subdirectory sometimes also contains aformatfile which describes only the contents of that subdirectory and which is not to be confused with this file.)- hooks/
This directory contains hook script templates and hook scripts, if any have been installed.
- locks/
Subversion uses this directory to house repository lock files, used for managing concurrent access to the repository.
- README.txt
This is a brief text file containing merely a notice to readers that the directory they are looking in is a Subversion repository.
Prior to Subversion 1.5, the on-disk repository
structure also always contained a dav
subdirectory. mod_dav_svn used this
directory to store information about
WebDAV activities—mappings of
high-level WebDAV protocol concepts to Subversion commit
transactions. Subversion 1.5 changed that behavior, moving
ownership of the activities directory, and the ability to
configure its location, into mod_dav_svn
itself. Now, new repositories will not necessarily have
a dav subdirectory
unless mod_dav_svn is in use and hasn't
been configured to store its activities database elsewhere.
See the section called “mod_dav_svn configuration directives”
for more information.
Of course, when accessed via the Subversion libraries, this otherwise unremarkable collection of files and directories suddenly becomes an implementation of a virtual, versioned filesystem, complete with customizable event triggers. This filesystem has its own notions of directories and files, very similar to the notions of such things held by real filesystems (such as NTFS, FAT32, ext3, etc.). But this is a special filesystem—it hangs these directories and files from revisions, keeping all the changes you've ever made to them safely stored and forever accessible. This is where the entirety of your versioned data lives.
[49] Strictly speaking, Subversion doesn't dictate that the versioned data live here, and there are known (albeit proprietary) alternative backend storage implementations which do not, in fact, store data in this directory.
[50] While it is often pronounced “fuzz-fuzz,” per Jack Repenning's rendition, this book assumes that the reader is thinking “eff-ess-eff-ess.”