Re: CVS and NFS: Questions

[Derek Robert Price]

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Richard Pfeiffer wrote:

|Regarding an NFS mounted repository:
|
|1)    Would these issues ONLY occur in matters where
|there was MORE THAN ONE server mounting the
|repository over NFS (because then you are dealing
|with the potential of locked files, etc) ?


Many of the issues are related to locking.  CVS uses a successful
mkdir(lockdir) to prevent other processes from creating locks.  As I
understand it, caching issues in NFS clients can cause two processes to
receive success codes from the mkdir call at the same time even though
one of them fails on the server end.  The two processes can then happily
start writing the same archive files, causing corruption.  I'm uncertain
whether this is an issue when only a single NFS client has mounted the
NFS server.  Regardless, you can work around this problem by setting the
LockDir= option in CVSROOT/config to point to a locally mounted
directory provided all the CVS clients are running on the same machine.

The other NFS issues that frequently arise are much more troublesome.
Apparently, especially with non-homogenous NFS implementations,
interoperability problems can cause random NUL bytes in the
communication stream to be written to the archive files.  This is
trouble and there is no workaround available.  This is why NFS is
usually discouraged for use with CVS.

|3)    If we are still at risk, then I assume that to
|avoid using NFS mounting, our repository must
|exist on the same server CVS is set up on?


Yes.

|4)     If so, this will negate our ability to
|quickly and safely re-mount the repository to
|another machine in case the main server fails.
|Any options to this?


RAID for local data redundancy and nightly backups?

YMMV.  Take my advice with a grain of salt and use it at your own risk.  :)

Derek

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