On 08/16/2016 08:42 AM, Ramana Raja wrote:
On Thursday, June 30, 2016 6:07 PM, Alexey Ovchinnikov
<aovchinni...@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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