Re: [openstack-dev] [Manila] FFE Request: glusterfs_native: negotiate volumes with glusterd

2015-03-31 Thread Ben Swartzlander

On 03/31/2015 10:54 AM, Csaba Henk wrote:

Hi Ben,

please find my answer inline.

- Original Message -

From: Ben Swartzlander b...@swartzlander.org
To: OpenStack Development Mailing List (not for usage questions) 
openstack-dev@lists.openstack.org
Sent: Monday, March 30, 2015 7:44:25 PM
Subject: Re: [openstack-dev] [Manila] FFE Request: glusterfs_native: negotiate 
volumes with glusterd

Thanks for going through the formal request process with this change.

One question I have that's not answered here is: what is the risk of
delaying this fix to Liberty? Clearly it needs to be fixed eventually,
but if we hold off and allow Kilo to ship as-is, will anything bad
happen? From the description above it sounds like the driver is
functional, and a somewhat awkward workaround (restarting the backend)
is required to deal with bug 1437176.

The risk is usability of the driver. To put it like that, driver is
architecturally broken -- storing all possible share backend instances
in a config parameter is not something should be seen in release code.


Will users be subjected to any upgrade problems going from Kilo to
Liberty if we don't fix this in Kilo? Will there be any significant
maintenance problems in the Kilo code if we don't change it?

OpenStack distributions might be tempted to backport the fix (to arrive at
a usable driver) in which case they take up a maintenance burden.

Csaba


Approved

-Ben Swartzlander


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Re: [openstack-dev] [Manila] FFE Request: glusterfs_native: negotiate volumes with glusterd

2015-03-31 Thread Csaba Henk
Hi Ben,

please find my answer inline.

- Original Message -
 From: Ben Swartzlander b...@swartzlander.org
 To: OpenStack Development Mailing List (not for usage questions) 
 openstack-dev@lists.openstack.org
 Sent: Monday, March 30, 2015 7:44:25 PM
 Subject: Re: [openstack-dev] [Manila] FFE Request: glusterfs_native: 
 negotiate volumes with glusterd
 
 Thanks for going through the formal request process with this change.
 
 One question I have that's not answered here is: what is the risk of
 delaying this fix to Liberty? Clearly it needs to be fixed eventually,
 but if we hold off and allow Kilo to ship as-is, will anything bad
 happen? From the description above it sounds like the driver is
 functional, and a somewhat awkward workaround (restarting the backend)
 is required to deal with bug 1437176.

The risk is usability of the driver. To put it like that, driver is
architecturally broken -- storing all possible share backend instances
in a config parameter is not something should be seen in release code.

 Will users be subjected to any upgrade problems going from Kilo to
 Liberty if we don't fix this in Kilo? Will there be any significant
 maintenance problems in the Kilo code if we don't change it?

OpenStack distributions might be tempted to backport the fix (to arrive at
a usable driver) in which case they take up a maintenance burden.

Csaba

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Re: [openstack-dev] [Manila] FFE Request: glusterfs_native: negotiate volumes with glusterd

2015-03-30 Thread Ben Swartzlander

On 03/30/2015 12:21 PM, Csaba Henk wrote:

Hi,

I'm applying for an FFE for change

https://review.openstack.org/162542 ,
glusterfs_native: negotiate volumes with glusterd.

The change in question is in the grey zone between
a bugfix and a feature. So, having it discussed with
the Manila community and our PTL, Ben Swartzlander,
we decided to defeat ambiguity by putting it
forward as an FFE.

While there is no explicit errant behavior with the
current glusterfs_native driver code that would be
addressed by this change, the situation is that the
current version of the driver is conceptually buggy
-- it does not meet consensual expectations what one
has against a driver. (It would be an overstatement
to call current create_share implementation a stub,
but the issue is something similar.)

One aspect of the limitation of create_share is
captured by this bug:

https://bugs.launchpad.net/manila/+bug/1437176 ,
glusterfs_native: Unable to create shares using newly
available GlusterFS volumes without restarting manila
share service

We are submitting the change as a fix for this.

Impact: the code adds a new, more general mechanism for
picking GlusterFS volumes for backing shares. The new code
is basically contained in one function, _pop_gluster_vol();
the rest of the diff is refactor to adjust the driver to
the new internal API. The impact is isolated and limited
to the glusterfs_native driver. The operation logic of the
driver is not affected beyond backing resource allocation of
in create_share. Unit test coverage is good.

Csaba Henk
Red Hat, Inc.


Thanks for going through the formal request process with this change.

One question I have that's not answered here is: what is the risk of 
delaying this fix to Liberty? Clearly it needs to be fixed eventually, 
but if we hold off and allow Kilo to ship as-is, will anything bad 
happen? From the description above it sounds like the driver is 
functional, and a somewhat awkward workaround (restarting the backend) 
is required to deal with bug 1437176.


Will users be subjected to any upgrade problems going from Kilo to 
Liberty if we don't fix this in Kilo? Will there be any significant 
maintenance problems in the Kilo code if we don't change it?




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