Since on the server side there truly is only 1 export.
And clients just access the same export through 2 different names,
I expect it would be safe.
-Sev
ps: But I think I'll wait for a simpler application (less negative
ramifications) to test it
BTW haven't seen this documented anywhere.
J. Bruce Fields wrote:
> On Mon, Nov 10, 2008 at 11:28:04AM -0800, Murata, Dennis wrote:
>
>> That really is the 64K question. During my initial testing, I exported
>> the parent directory. Now I am explicitly exporting the installation
>> directories, where I see the exportfs message. In the messages log file
>> on the server the mount request from the client is always the actual
>> directory.
>>
>
> I don't see how this would be "unsafe"--if it works, go for it.
>
> One potential trap: it's using the same client list and export options
> for both, so if you think you can make one of them read-only and one of
> them writeable, for example, you'll be disapointed.
>
> --b.
>
>
>> Wayne
>>
>>
>>> -----Original Message-----
>>> From: Sev Binello [mailto:sev@xxxxxxx]
>>> Sent: Monday, November 10, 2008 1:04 PM
>>> To: Murata, Dennis
>>> Cc: J. Bruce Fields; nfs@xxxxxxxxxxxxxxxxxxxxx
>>> Subject: Re: [NFS] export dir thru 2 diff path names
>>>
>>> Hi -
>>> Yeah, I see.
>>> So it actually looks like you can do this.
>>> I'm not 100% sure if safe --though it looks it -- so I'll
>>> probably not use it for this application.
>>>
>>> Thanks
>>> -Sev
>>>
>>> Murata, Dennis wrote:
>>>
>>>> That is correct, exportfs only shows the actual directory.
>>>>
>>> The client
>>>
>>>> seems to be able to mount the directory with either.
>>>>
>>>> Wayne
>>>>
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: Sev Binello [mailto:sev@xxxxxxx]
>>>>> Sent: Monday, November 10, 2008 12:51 PM
>>>>> To: Murata, Dennis
>>>>> Cc: J. Bruce Fields; nfs@xxxxxxxxxxxxxxxxxxxxx
>>>>> Subject: Re: [NFS] export dir thru 2 diff path names
>>>>>
>>>>> 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@xxxxxxxxxxxxxxx
>>>>>>> [mailto:linux-nfs-owner@xxxxxxxxxxxxxxx] On Behalf Of Sev Binello
>>>>>>> Sent: Monday, November 10, 2008 11:06 AM
>>>>>>> To: J. Bruce Fields; nfs@xxxxxxxxxxxxxxxxxxxxx
>>>>>>> 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@xxxxxxx
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
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>>>>>>>
>>>>> --
>>>>>
>>>>> Sev Binello
>>>>> Brookhaven National Laboratory
>>>>> Upton, New York
>>>>> 631-344-5647
>>>>> sev@xxxxxxx
>>>>>
>>>>>
>>>>>
>>>>>
>>>
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