Re: [SVN-MIGRATION] Steps for the SVN migration

On Jul 25, 2008, at 7:18 PM, Lars Strojny wrote:
> 1.) Do we want to use mod_dav_svn or svnserve, the subversion daemon?
>
> Pro:
>   * Allows to browse the repository with a normal webserver, very  
> handy
>   * Allows to use mod_authz_svn for fine grained access (different
>     format from the current format, but easily to read)
>   * Is writable with normal WebDAV clients which might be a handy
>     feature for those, who do not want to bother with learning SVN
>     (those who do documentation translations, website updates, etc.)
>
> Contra:
>   * Might be slower
>   * Forces us to use Apache 2, which we, as I heard, currently do not
>     use

I've always personally preferred svnserve. It has Authz support these  
days and I think PHP's Apache servers have enough to deal with as it is.

> 2.) Single repository, multiple repositories. Do we want to use a  
> single
> repository for all things PHP, including PEAR, PECL etc.?
>
> Pro:
>   * It is how it is currently
>   * Only one repository to maintain and administer (e.g. hooks are
>     configured for everything or for nothing)
>
> Contra:
>   * Multiple repositories might be easier to scale, as they can be
>     distributed on various hosts. Not sure if this is likely to become
>     an issue
>   * Easier to include new projects and to move current projects to
>     another hosts if the situation requires such a change
>   * One repository itself does not become that huge and can be shared
>     over partitions, discs (while this is possible with symlinking old
>     revision data too, it is not very handy)

I much prefer splitting the top-level projects (pear, pecl, php-src,  
php-doc, everything else) into separate repositories. It both eases  
the conversion and allows for future expansion. I think it will  
simplify rather than complexify the hooks, and we can maintain the  
hooks for most projects in a kind of "meta" repository. CVS already  
effectively functions this way; SVN is geared a bit more towards  
having multiple repositories. It would also help with keeping SVN  
revision numbers from scaling into the hundreds of thousands within  
days.

> 3.) Directory structure: We will have the classical layout
> (branches/tags/trunk), but what about subdirectories in tags like
> releases, and feature tags. What about a developer folder in  
> branches to
> allow developer specific branches?

I'd like to see some "outside the box" thinking here. SVN gives us the  
flexibility to use any structure we want. I wouldn't be averse to  
seeing php-src, for one example, look like this:
php-src/
  PHP_6/
  PHP_5_3/
  PHP_4/
  release_tags/
  old_branches/
  developer_branches/
  other_tags/
  other_branches/

There's not even a trunk/ or HEAD/ in there, one might notice. Why  
should there be? svn's history-preserving copy and move commands also  
make management of such branches deceptively simple.

> 4.) Do we want to sync to CVS in the first time with a hook to allow  
> use
> to switch back just in case of an unforeseeable failure with the
> Subversion repository?

With a redesign of the directory structure as suggested above, this  
becomes difficult at best, requiring a manual mapping of SVN  
directories to CVS branches. But it could and probably should be done  
for at least a month's time post-conversion. We have the people to  
make it work.

> Research
> ========
>     2. What would be the alternative to mod_authz_svn if we decide to
>        use svnserve?

svnserve now has native authz database support.

>     3. How can we improve the speed of the conversion process to make
>        the outage of the tree as short as possible. Does Gwynne need
>        hardware help here, can we provide resources (machines) to  
> help?

Definitely. This is a 2008 iMac running Mac OS X 10.5.4, 2.4 Ghz Intel  
Core 2 Duo, 2 GB RAM. It's fine for my personal purposes, but a  
project like this strains my CPU something awful.

>     4. What scripts to work with CVS are there, how can they be
>        converted to work with Subversion?

Off the top of my head, anything in CVSROOT, the cvsclean script in  
php-src.

-- Gwynne, Daughter of the Code
"This whole world is an asylum for the incurable."