Re: [NFS] export dir thru 2 diff path names

[Sev Binello <sev-IGkKxAqZmp0@public.gmane.org>]

Murata, Dennis wrote:
> I just tested this on a SL4.7 (RHEL 4.7 variant) using a RHEL 4.4 nfs
> server.  I did get the messages from exportfs about duplicate export
> entries.  On the client I was able to mount both the symlink and the
> actual directory.  They look like separate mounts.  There are two
> entries in /proc/mounts and in /etc/mtab, one with the actual directory
> path, one with the symlink path.  I am using autofs to mount the
> directories, not hardcoded.  Are you using newer distributions?
>   
I tested on RHEL 4.6.
Interesting that you can still mount either one.
On the server an exportfs only shows the real path as exported.

> What problems will I cause by doing this?  I am using the symlink path
> as the installation path for an application.  The idea is a newer
> version can be installed into a different directory, then after testing
> the symlink will be changed to the new installation.  Other applications
> that reference the application will always use the symlink path, as well
> as any user scripts.
>
> Wayne 
>
>   
>> -----Original Message-----
>> From: linux-nfs-owner@vger.kernel.org 
>> [mailto:linux-nfs-owner@vger.kernel.org] On Behalf Of Sev Binello
>> Sent: Monday, November 10, 2008 11:06 AM
>> To: J. Bruce Fields; nfs@lists.sourceforge.net
>> Subject: Re: [NFS] export dir thru 2 diff path names
>>
>> J. Bruce Fields wrote:
>>     
>>> On Mon, Nov 10, 2008 at 10:55:48AM -0500, Sev Binello wrote:
>>>   
>>>       
>>>> Well the simplest approach doesn't work.
>>>> i.e put symb link and actual path in the export file & try 
>>>>         
>> exporting 
>>     
>>>> it Exportfs dereferences the link and states that 
>>>>         
>> duplicates are not allowed.
>>     
>>>>     
>>>>         
>>> OK, makes sense.
>>>
>>> You could mount --bind the filesystem at the other location 
>>>       
>> instead of 
>>     
>>> symlinking.
>>>
>>> The filehandles given to the client will be the same across the two 
>>> exports.  If you mount both from the same client, behavior may vary 
>>> across different clients (for example, as to whether they 
>>>       
>> attempt to 
>>     
>>> share caches between the two), but I think it'd work.
>>>
>>> (The question "why??!!??" does come to mind, though.)
>>>
>>>   
>>>       
>> Need to make a path change to how file systems are mounted 
>> and exported on the servers This then required a wholesale 
>> change to clients so they mount  the correct path.
>>  Not an issue for linux.
>> But since we don't administer windows pcs and they also mount 
>> the same file system, wanted to see if we could let them stay 
>> the way they were for now.
>>
>> We're just going to go ahead and  have to coordinate this 
>> with windows guys.
>>
>> -Sev
>>     
>>> --b.
>>>
>>>   
>>>       
>>>> -Sev
>>>>
>>>> J. Bruce Fields wrote:
>>>>     
>>>>         
>>>>> On Fri, Nov 07, 2008 at 12:44:25PM -0500, Sev Binello wrote:
>>>>>   
>>>>>       
>>>>>           
>>>>>> Can anyone tell me if it's ok to export the same file system 
>>>>>> through 2 different paths ( one is a link) ?
>>>>>>     
>>>>>>         
>>>>>>             
>>>>> I actually don't know.  You could try it and tell us what 
>>>>>           
>> you find 
>>     
>>>>> out....
>>>>>
>>>>> If you're exporting something *containing* the symlink 
>>>>>           
>> and expecting 
>>     
>>>>> the client to traverse into the filesystem, be aware that 
>>>>>           
>> symlinks 
>>     
>>>>> over NFS are actually interpreted (and followed) on the 
>>>>>           
>> client--so 
>>     
>>>>> they're interpreted as *client-side* paths, not server-side.
>>>>>
>>>>> If the path you're exporting is itself a symlink--it probably 
>>>>> depends on how nfs-utils treats symlinks found in 
>>>>>           
>> /etc/exports.  I'd 
>>     
>>>>> have to try it or check the code.
>>>>>
>>>>> Another way to export the filesystem in two different 
>>>>>           
>> places would 
>>     
>>>>> be with mount --bind.
>>>>>
>>>>> --b.
>>>>>   
>>>>>       
>>>>>           
>>>> --
>>>>
>>>> Sev Binello
>>>> Brookhaven National Laboratory
>>>> Upton, New York
>>>> 631-344-5647
>>>> sev-IGkKxAqZmp0@public.gmane.org
>>>>
>>>>     
>>>>         
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-- 

Sev Binello
Brookhaven National Laboratory
Upton, New York
631-344-5647
sev-IGkKxAqZmp0@public.gmane.org


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