Re: Clarifications: CVS Import Bug - Please Respond

[Derek Price]

Bogdan,

The problem is that neither lock is working.  If CVS's directory-level
locks were in place, you would see no problems at all. If only the RCS
locks were in place, you might occassionally see change sets get
overwritten, but you should see no file corruption.

As for why the RCS locks are not working with your NFS implementation, I
cannot really tell you, except to say that NFS file locking is
notoriously unreliable, which is why CVS uses its own style of directory
level locks in the first place, and we generally recommend that CVS
repositories not be stored on NFS servers.  IIRC, many of the problems
stem from using non-homogenous sytems, e.g. a Solaris NFS Server and a
Linux NFS client, or a NetApp accessed from a client it was not tested
thoroughly with.  I do know of several companies out there that do store
their CVS repositories on NFS servers without problems, but as I
understand it, they are using high-end NetApps fully tested with their
NFS clients.

Other problems that have been reported stemming from non-homogenous NFS
setups include random NUL bytes inserted in files on commit.  Don't know
if there are others.

Regards,

Derek


Oproescu Bogdan (KTXA 3) wrote:

>   Hi Derek and all, 
>
>   So, which one is the problem here: is it that RCS-style locks 
>   don't work correctly on their NFS-mounted file systems, or is it 
>   simply that the source code of CVS is incorrect and omits File 
>   and Directory locking prior to cvs imports? You described a fix
>   for the second issue when CVS source code is incorrect, but if 
>   this was also the case how would we make RCS locks work on NFS? 
>
>   Cheers & Regards, Bogdan 
>
>   Bogdan Oproescu 
>
>   CREDIT SUISSE FINANCIAL SERVICES
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>
>-----Original Message-----
>From: Derek Price [mailto:derek@ximbiot.com] 
>Sent: Wednesday, August 10, 2005 11:18 PM
>To: Larry Jones
>Cc: Oproescu Bogdan (KTXA 3); 'bug-cvs@nongnu.org'; 'Bernd Jendrissek'
>Subject: Re: Next Steps: CVS Import Bug - Please Respond
>
>Larry Jones wrote:
>
>  
>
>>Derek Price writes:
>> 
>>
>>    
>>
>>>Actually, though atomicity and locking are disjoint concepts, it sure
>>>looks like import is skipping directory locks.  Please see my previous post.
>>>   
>>>
>>>      
>>>
>>Our posts crossed in the e-mail.  I'm simply astounded -- if anyone else
>>had said it, I don't think I would have believed it.  I can't believe no
>>one has ever reported it before.
>> 
>>
>>    
>>
>
>I just waded through the code and can barely believe it myself.  I had
>only meant to glance through to refresh my memory...
>
>  
>
>>It's also possible that the RCS-style locks don't work correctly on
>>their NFS-mounted file system.
>> 
>>
>>    
>>
>
>Perhaps no one has reported this before because the RCS locks have been
>saving people in general.  This particular combination of an NFS mounted
>repo and heavily used imports may be rare.
>
>Regards,
>
>Derek
>
>  
>


-- 
Derek R. Price
CVS Solutions Architect
Ximbiot <http://ximbiot.com>
v: +1 717.579.6168
f: +1 717.234.3125
<mailto:derek@ximbiot.com>