Subversion & NAS

[Greg Thomas <Gr...@TheThomasHome.co.uk>]

Hi,

We're currently using CVS for about a dozen developers with a
repository ~1GB big (though a lot of that is Windows DLLs - storing
these helps resolve DLL hell problems, IME). I'd like to migrate this
to Subversion, and to that effect I've been offered a properly managed
system, but, because it is policy, the underlying file system will be
an EMC Celerra (sp?) NAS system. 

I know from plenty of discussion on the lists that Subversion (or more
accurately, the underlying Berkeley DB) doesn't work well on networked
file systems - http://subversion.tigris.org/project_faq.html#nfs links
to a Sleepycat page which has two provisos:

1: "Databases, log files, and temporary files may be placed on remote
filesystems, as long as the remote filesystem fully supports standard
POSIX filesystem semantics".

2: "NFS-mounted databases cannot be accessed from more than one
Berkeley DB environment at a time"

Would I be right in assuming that if 
(a) the EMC NAS "fully supports standard POSIX filesystem semantics",
and 
(b) access to the DB is only from the one system (i.e. access to the
repository would be using ra_dav, with ra_local only used for access
from the system hosting Apache)

we would be all right? Has anyone had any practical experience in this
sort of scenario?

TIA,

Greg

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RE: Subversion & NAS

[Alan <ju...@alan2.com>]

 If you look at the FAQ on the Berkeley DB site, the problem with shared media
is that Berkeley DB uses mmap to map a file into memory, and there is no way to
share this memory between nodes, so it is possible for nodes to conflict no
matter how your storage is shared. The problems are in sharing of memory not the
media itself. This is how I understood the faq anyways.

-Alan

-----Original Message-----
From: Sergey A. Lipnevich [mailto:sergey@optimaltec.com] 
Sent: Monday, November 24, 2003 9:09 PM
To: Greg Thomas; users@subversion.tigris.org
Subject: Re: Subversion & NAS

You should probably push for SAN then, EMC does that of course, but I'm not sure
about Celerra. Or use something like iSCSI to make it look like DAS to Berkeley
DB.
HTH.

Sergey.

Greg Thomas wrote:
> We're currently using CVS for about a dozen developers with a 
> repository ~1GB big (though a lot of that is Windows DLLs - storing 
> these helps resolve DLL hell problems, IME). I'd like to migrate this 
> to Subversion, and to that effect I've been offered a properly managed 
> system, but, because it is policy, the underlying file system will be 
> an EMC Celerra (sp?) NAS system.



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Re: Subversion & NAS

["Sergey A. Lipnevich" <se...@optimaltec.com>]

You should probably push for SAN then, EMC does that of course, but I'm
not sure about Celerra. Or use something like iSCSI to make it look like
DAS to Berkeley DB.
HTH.

Sergey.

Greg Thomas wrote:
> We're currently using CVS for about a dozen developers with a
> repository ~1GB big (though a lot of that is Windows DLLs - storing
> these helps resolve DLL hell problems, IME). I'd like to migrate this
> to Subversion, and to that effect I've been offered a properly managed
> system, but, because it is policy, the underlying file system will be
> an EMC Celerra (sp?) NAS system. 



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