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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

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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