使用svnsync实现版本库的同步备份

操作流程：

• 1、在要备份的机器上建立版本库：svnadmin create test
• 2、进入hooks目录：cd test/hooks/
• 3、创建pre-revprop-change文件：cp pre-revprop-change.tmpl pre-revprop-change
• 4、修改pre-revprop-change权限：chomd +x pre-revprop-change
  5、修改文件：vi pre-revprop-change
  为 echo “Changing revision properties other than svn:log is prohibited” >&2
  exit 0（1修改为0）
• 6、同步初步：
  svnsync init file:///home/test/svn/test svn://10.10.10.1/
  svnsync: Destination repository is already synchronizing from ’svn://10.10.10.1′
• 7、实现同步：
  svnsync sync file:///home/test/svn/test –username username –password password1

 遇到的问题与解决方法：

问题1

Failed to get lock on destination repos, currently held by 'bug1.corp.scmbbs.com:0c424c20-2e3b-0410-bd34-7fdd53c25d02'
svnsync: Couldn't get lock on destination repos after 10 attempts

这个时候可能属性被锁了，删掉属性：

svn propdel svn:sync-lock --revprop -r0 file:///home/backup/svn/svnsync/SMP

删除成功后，再试一遍基本就可以了。
如果反复操作都是同样错误的话，有可能是你的svn安装的有问题，重新安装一遍就好了，俺就是这样。

问题2

[test@localhost sync]$ svnsync sync file:///home/test/svn/test --username username
--password username123
svnsync: Destination HEAD (593) is not the last merged revision (592);
have you committed to the destination without using svnsync?

<搜索结果>

It looks like svnsync committed up through r35, but somehow it didn't
track this in its 'svn:sync-last-merged-revision' property, which is
still lagging at 30. Just modify that property on revision 0 to be
35:
$ svn proplist -v --revprop -r0 https://powermock.googlecode.com/svn
$ svn propset --revprop -r0 svn:sync-last-merged-revision 35
https://powermock.googlecode.com/svn
Then you should be able to keep syncing.

[test@localhost sync]$ svn proplist -v --revprop -r0 file:///home/test/svn/test --username username --password username123
Unversioned properties on revision 0:
svn:sync-from-uuid : 729778b4-f309-46d9-b0ab-184bf13f9df8
svn:sync-last-merged-rev : 592
svn:date : 2008-11-25T04:02:56.364852Z
svn:sync-from-url : svn://10.10.10.1

[test@localhost sync]$ svn propset --revprop -r0 svn:sync-last-merged-revision 593 file:///home/test/svn/test
property 'svn:sync-last-merged-revision' set on repository revision 0

test@localhost sync]$ svn propset --revprop -r0 svn:sync-last-merged-rev 593 fi
le:///home/test/svn/test
property 'svn:sync-last-merged-rev' set on repository revision 0

[test@localhost sync]$ svnsync sync file:///home/test/svn/test --username username
--password username123
Committed revision 594.
Copied properties for revision 594.
svnsync: Expected 'revprops', found 'failure'

相关介绍

本文介绍利用svnsync来同步版本库，达到备份版本库的目的
要用到两个命令
1、svnsync init
初始化，建立目标库和源库之间的同步关系
命令格式 svnsync init 目标库URL 源库URL
2、svnsync sync
真正的同步
命令格式 svnsync sync 目标库URL
目标
本次实现的是版本库的远程自动备份，将版本库备份到另一台机器上
假设我们要同步的源版本库为 http://192.168.0.1/svn/proj1　位于机器A，具体路径我们不必理会，因为我们使用http协议
目标库在机器B，file:///svn/proj1，这个为了简单和安全，我们使用file://协议，proj1是我们用svnadmin create命令创建的一个空库
过程
1、在机器B上，创建目标库
mkdir /svn
svnadmin create /svn/proj1
2、在机器B上，修改目标库的脚本pre-revprop-change
进入/svn/proj1/hooks/
cd /svn/proj1/hooks/
cp pre-revprop-change.tmpl pre-revprop-change
chmod +x pre-revprop-change
vi pre-revprop-change

REPOS=”$1″
REV=”$2″
USER=”$3″
PROPNAME=”$4″
ACTION=”$5″
if [ "$ACTION" = "M" -a "$PROPNAME" = "svn:log" ]; then exit 0; fi
echo “Changing revision properties other than svn:log is prohibited” >&2
exit 1
原脚本的意思是如果修改的是svn:log属性，将允许修改，返回0；否则，不允许，返回1
我们要将它改为允许修改所有的属性，在脚本中直接返回0，新的脚本如下：

exit 0;
3、初始化
在机器B上
svnsync init file:///svn/proj1 http://192.168.0.1/svn/proj1 会提示输入用户名和密码，这里提供的用户名和密码是可以完全读取http://192.168.0.1/svn/proj1的用户名和密码
4、同步
在机器B上
svnsync sync file:///svn/proj1

依然会提示输入用户名和密码，不过，你可以在这个命令之后加上 username 、password参数，
例如svnsync sync file:///svn/proj1 –username username –password password

官方说明

==== What Is It? ====

svnsync is a tool for creating and maintaining read-only mirrors of
subversion repositories. It works by replaying commits that occurred
in one repository and committing it into another.

==== Basic Setup ====

First, you need to create your destination repository:

$ svnadmin create dest

Because svnsync uses revprops to keep track of bookkeeping information
(and because it copies revprops from the source to the destination)
it needs to be able to change revprops on your destination repository.
To do this you’ll need to set up a pre-revprop-change hook script that
lets the user you’ll run svnsync as make arbitrary propchanges.

$ cat <<’EOF’ > dest/hooks/pre-revprop-change
#!/bin/sh
USER=”$3″

if [ "$USER" = "svnsync" ]; then exit 0; fi

echo “Only the svnsync user can change revprops” >&2
exit 1
EOF
$ chmod +x dest/hooks/pre-revprop-change

$ svnsync init –username svnsync file://`pwd`/dest \
http://svn.example.org/source/repos
Copied properties for revision 0
$

Note that the arguments to ’svnsync init’ are two arbitrary repository
URLs. The first is the destination, which must be empty, and the second
is the source.

Now you can just run the ’svnsync sync’ command to synchronize pending
revisions. This will copy any revisions that exist in the source repos
but don’t exist in the destination repos.

$ svnsync sync file://`pwd`/dest
Committed revision 1.
Copied properties for revision 1.
Committed revision 2.
Copied properties for revision 2.
Committed revision 3.
Copied properties for revision 3.
…

==== Locks ====

If you kill a sync while it’s occurring there’s a chance that it might
leave the repository “locked”. svnsync ensures that only one svnsync
process is copying data into a given destination repository at a time
by creating a svn:sync-lock revprop on revision zero of the destination
repository. If that property is there, but you’re sure no svnsync is
actually running, you can unlock the repository by deleting that revprop.

$ svn pdel –revprop -r 0 svn:sync-lock file://`pwd`/dest

==== FAQ ====

Q: So what can I do with this thing anyway?

A: Well, anything that’s read-only. As long as you don’t commit changes
to the destination repository you’re all set. This means destination
repositories are good for providing offsite mirrors, read-only mirrors,
etc.

Q: What if I want to check out from a mirror, but commit to the master?

A: That’s possible, but requires some gymnastics. You see, each repository
has its own UUID, which is stored in the working copy, so if you check
out from the mirror, and then do a ’svn switch –relocate’ to point to
the master it’ll error out. To make this work you need to make sure that
the mirrors have the same UUID as the master. You can read a repository
UUID with ’svnlook uuid’ or ’svn info’, and change it with
’svnadmin setuuid’.

Once both the mirror and master repositories have the same UUID you can
safely check out from the mirror and commit to the master, all you have
to do is do a ’svn switch –relocate’ to point your working copy to the
master before a commit.

Note that you should NEVER commit changes to a mirror other than
via svnsync, so to avoid accidentally doing so you may want to add
a start-commit hook script that disallows commits from users other
than the one you run svnsync as, and a pre-lock hook script that
disallows all filesystem lock requests (svnsync will never create
these locks, but its attempt to commit can be blocked by them).

Q: What version of Subversion is required to use svnsync?

A: The source repository must be running Subversion 1.4 or newer, since
svnsync uses a new RA layer command that was added in 1.4. On the other
hand, the destination repository can be any version of Subversion, since
all svnsync is doing is committing changes using the regular RA APIs.

Q: Do I need to run svnsync on the same machine as one of the
repositories?

A: While you do need direct access to the destination repository to
set up a pre-revprop-change hook script, after that point svnsync
communicates with both repositories through the same “repository
access” layer that svn uses to connect to remote repositories. So
svnsync does not have to be run on the same machine as either
repository; it can communicate with both repositories over any of
Subversion’s RA protocols (svn://, svn+ssh://, http://, https://,
or file:///). In fact, you don’t need any special permissions on
the source repository at all.

Q: How does svnsync deal with parts of the master repository that I’m not
authorized to read?

A: svnsync will simply not copy parts of the repository that you
cannot read; files copied from “private” parts of the repository
into “public” parts will look as if they have been added from
scratch. If a revision only modifies files that you cannot read,
it will appear to be empty. (Just like with “svn log”, log
messages from revisions you cannot read part of will be empty.)

Q: Can I mirror a subdirectory of a master repository?

A: As of Subversion 1.5, it is possible to limit svnsync to a subdirectory
of the master repository.
This is most useful when the master repository is organized in projects,
and you want to sync only one project.
Example showing svnsync of project1 in the master repository:
/project1
/branches
/tags
/trunk
/project2
/branches
/tags
/trunk

The following commands will sync all changes in /project1 to the target
repository:
$ svnsync init file://`pwd`/dest http://svn.example.org/source/repos/project1
$ svnsync sync file://`pwd`/dest

Note: this syntax only allows you to limit the scope of svnsync to
/project1. It does not:
- allow you to sync two or more projects from the master repository.
- recognize renames of project1. Example, if the original name of project1
was secretproject, only the changes starting from the revision in which the
rename to project1 was committed will be synced.

If you need any of these abilities right now, you may want to look into SVK
(http://svk.bestpractical.com/).

Q: What happens when I change a revprop on the master server?

A: That depends, did you change it on a revision that had already been
mirrored or one that’s still waiting to be mirrored. If the revision
hasn’t been mirrored yet, the new revprop will just get copied across
normally when the next sync happens. If not, then you’ve got a small
problem. You see, since revprops aren’t versioned, there’s no way to
detect (via the Subversion RA APIs anyway) that it’s been changed, so
the next time you run a sync svnsync has no way to tell that it has
changed. There is a way for you to build your own solution though,
just use the ’svnsync copy-revprops’ command. The usual technique is
either to put an explicit call to it in your master repository’s
post-revprop-change script, or to have the post-revprop-change script
record the fact that a change occurred, and then later on have some
job look through the list of changes and copy them over for you.

Q: How can I relocate the source repository for svnsync?

A: A simple way to relocate a svnsync-ed repository is to change the
revision property (of the mirror) that stores the source repository’s
URL. Just use this command:

$ svn propset svn:sync-from-url –revprop -r 0 NEW_SOURCE_URL MIRROR_URL

NOTE: Don’t use `svn propedit`, because editors may append an EOL
character to NEW_SOURCE_URL that will lead svnsync complaining
“svnsync: Malformed URL for repository”.