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On 08/16/2016 08:42 AM, Ramana Raja wrote:
> On Thursday, June 30, 2016 6:07 PM, Alexey Ovchinnikov <aovchinnikov at mirantis.com> wrote:
>>
>> Hello everyone,
>>
>> here I will briefly summarize an export update problem one will encounter
>> when using nfs-ganesha.
>>
>> While working on a driver that relies on nfs-ganesha I have discovered that
>> it
>> is apparently impossible to provide interruption-free export updates. As of
>> version
>> 2.3 which I am working with it is possible to add an export or to remove an
>> export without restarting the daemon, but it is not possible to modify an
>> existing
>> export. So in other words if you create an export you should define all
>> clients
>> before you actually export and use it, otherwise it will be impossible to
>> change
>> rules on the fly. One can come up with at least two ways to work around
>> this issue: either by removing, updating and re-adding an export, or by
>> creating multiple
>> exports (one per client) for an exported resource. Both ways have associated
>> problems: the first one interrupts clients already working with an export,
>> which might be a big problem if a client is doing heavy I/O, the second one
>> creates multiple exports associated with a single resource, which can easily
>> lead
>> to confusion. The second approach is used in current manila's ganesha
>> helper[1].
>> This issue seems to be raised now and then with nfs-ganesha team, most
>> recently in
>> [2], but apparently it will not be addressed in the nearest future.
>
> Frank Filz has added support to Ganesha (upstream "next" branch) to
> allow one to dynamically update exports via D-Bus. Available since,
> https://github.com/nfs-ganesha/nfs-ganesha/commits/2f47e8a761f3700

This is awesome news! Unforunately there's no time to update the 
container driver to use this mechanism before Newton FF, but we can 
provide feedback and plan this enhancement for Ocata.

-Ben


> It'd be nice if we can test this feature and provide feedback.
> Also, ML [2] was updated with more implementation details.
>
> Thanks,
> Ramana
>
>>
>> With kind regards,
>> Alexey.
>>
>> [1]:
>> https://github.com/openstack/manila/blob/master/manila/share/drivers/ganesha/__init__.py
>> [2]: https://sourceforge.net/p/nfs-ganesha/mailman/message/35173839
>>
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