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Posted to users@subversion.apache.org by Neil Bird <ne...@jibbyjobby.co.uk> on 2011/10/26 13:23:46 UTC
SVN repo cross-platform compatibility
Whilst suffering a subversion server outage, it's made me wonder: we
currently produce nightly backups of our repos via 'hotcopy' from the
server's local drive to a network store.
If the server were to die, would I be able to take those copies and place
them under a server on a new box *with a different OS*? Or would I have to
create a temporary server with the original OS, copy them to that, and
svndump them and import them elsewhere?
In this case, it's a Solaris server, dunno what processor [I'll check
when it's back up!], and I'd consider moving it to an x86 Linux server.
--
[neil@fnx ~]# rm -f .signature
[neil@fnx ~]# ls -l .signature
ls: .signature: No such file or directory
[neil@fnx ~]# exit
Re: SVN repo cross-platform compatibility
Posted by Nico Kadel-Garcia <nk...@gmail.com>.
On Wed, Oct 26, 2011 at 7:23 AM, Neil Bird <ne...@jibbyjobby.co.uk> wrote:
>
> Whilst suffering a subversion server outage, it's made me wonder: we
> currently produce nightly backups of our repos via 'hotcopy' from the
> server's local drive to a network store.
>
> If the server were to die, would I be able to take those copies and place
> them under a server on a new box *with a different OS*? Or would I have to
> create a temporary server with the original OS, copy them to that, and
> svndump them and import them elsewhere?
>
> In this case, it's a Solaris server, dunno what processor [I'll check when
> it's back up!], and I'd consider moving it to an x86 Linux server.
Never do this by direct filesystem replication. "hotcopy" is somewhat
better. Issues with transfer via hotcopy include the fact that hotcopy
*does not* replicate file permissions and file ownership, it simply
copies them as whoever runs the "svnadmin hotcopy" command. That can
cause *enormous* problems in various configurations. And between
operating systems, the "hook" or "conf" tools that are incompatible
between the system's scripting languages. Worse, if your new OS does
not have an equal or greater Subversion major release, the hotcopy
will likely be incompatibile with the new OS.
I spent one *hell* of a time last year, when someone had been running
a handbuilt Subversion binary with a manually built and awkwardly
configured service, and I was prevented by "policy" from updating the
Subversion on RHEL 5.x, which was Subversion 1.4.x, to the publicly
available Subversion 1.6.x from RPMforge. So I was compelled for
political reasons, not techinical reasons, to continue to support the
older and more fragile environments, and not permitted to migrate them
for quite a long time.
That said, you also face a very dangerous "split brain" issue if you
simply set up the replicated, up to 24 hours out of date copy
elsewhere and set up the same uuid, so users who've already checked
out or checked in changes since the last snapshot will have a local
working copy that is dangerously out of sync with the replica. Two
diferent working copies can wind up with different ideas of whatever
revisions occurred, and may wind up out of sync between the two
repositories.
All that said, Solaris=>Linux is fortunately a fairly easy migration.
Similar releases of Subversion are available, unless you have a
seriously out of date system that policy forbids you from updating.
The trick is to keep the *non* db files, the hooks and conf files,
mirrored separately and regularly, and keep a Linux read-only
repository mirrored with "svnsync", Properly managed, the "svnsync"
can even be triggered to occur after every successful commit, and
always keep you within one revision of the master repository.
If you have to do the replica, *use a new uuid* and inform your users
that they have to deal with a new repository.
Re: SVN repo cross-platform compatibility
Posted by Philip Martin <ph...@wandisco.com>.
Stefan Sperling <st...@elego.de> writes:
> With BDB repositories, it will not work, so you should dump/load.
Is that right? According to the documentation:
http://download.oracle.com/docs/cd/E17076_02/html/gsg/C/databaseLimits.html
the BDB database files are portable. I think the BDB environment files
are platform dependent, but they can be deleted/recreated on the new
platform by running recover.
--
Philip
Re: SVN repo cross-platform compatibility
Posted by Stefan Sperling <st...@elego.de>.
On Wed, Oct 26, 2011 at 02:13:35PM +0100, Neil Bird wrote:
> Around about 26/10/11 12:28, Stefan Sperling typed ...
> >With FSFS repositories, yes, it will work if you copy the files
> >onto the new system from the network store (it might not if you try
> >to mount a disk from the old system on the new system directly, then
> >it depends on OS filesystem support and endianness handling).
>
> They are FSFS; however, if endianness is *ever* an issue, then
> it'll *always* be an issue, surely?
>
> If it's currently a big-endian SPARC, and I merely copy the repo.
> dirs. onto a little-endian x86, if endianness is a problem then that
> won't work.
It will be fine if you copy across the network (this handles the
differences in endianess just fine).
I don't know whether or not it will work if you directly access
the filesystem created by solaris sparc with linux x86. It might
work, but I haven't tried.
Re: SVN repo cross-platform compatibility
Posted by Neil Bird <ne...@jibbyjobby.co.uk>.
Around about 26/10/11 12:28, Stefan Sperling typed ...
> With FSFS repositories, yes, it will work if you copy the files
> onto the new system from the network store (it might not if you try
> to mount a disk from the old system on the new system directly, then
> it depends on OS filesystem support and endianness handling).
They are FSFS; however, if endianness is *ever* an issue, then it'll
*always* be an issue, surely?
If it's currently a big-endian SPARC, and I merely copy the repo. dirs.
onto a little-endian x86, if endianness is a problem then that won't work.
All I have is:
$ uname -a
SunOS hostname 5.10 Generic_139555-08 sun4u sparc SUNW,Sun-Fire-V240
.. and that doesn't really help me!
--
[neil@fnx ~]# rm -f .signature
[neil@fnx ~]# ls -l .signature
ls: .signature: No such file or directory
[neil@fnx ~]# exit
Re: SVN repo cross-platform compatibility
Posted by Stefan Sperling <st...@elego.de>.
On Wed, Oct 26, 2011 at 12:23:46PM +0100, Neil Bird wrote:
>
> Whilst suffering a subversion server outage, it's made me wonder:
> we currently produce nightly backups of our repos via 'hotcopy' from
> the server's local drive to a network store.
>
> If the server were to die, would I be able to take those copies
> and place them under a server on a new box *with a different OS*?
> Or would I have to create a temporary server with the original OS,
> copy them to that, and svndump them and import them elsewhere?
>
> In this case, it's a Solaris server, dunno what processor [I'll
> check when it's back up!], and I'd consider moving it to an x86
> Linux server.
With FSFS repositories, yes, it will work if you copy the files
onto the new system from the network store (it might not if you try
to mount a disk from the old system on the new system directly, then
it depends on OS filesystem support and endianness handling).
With BDB repositories, it will not work, so you should dump/load.