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It depends on the "corruption" that u are willing to tolerate. Sigterm means the process just terminates, what if said process was 3/4 through some operation (create_volume for example)??

Personally I am willing to tolerate zero corruption, reliability and consistency are foundational things for me. Others may be more tolerant though, seems worth further discussion IMHO.

Sent from my really tiny device...

On Dec 15, 2013, at 8:39 PM, "iKhan" <ik.ibadkhan at gmail.com<mailto:ik.ibadkhan at gmail.com>> wrote:

How about sending SIGTERM to child processes and then starting them? I know this is the hard way of achieving the objective and SIGHUP approach will handle it more gracefully. As you mentioned it is a major change, tentatively can we use SIGTERM to achieve the objective?


On Mon, Dec 16, 2013 at 9:50 AM, Joshua Harlow <harlowja at yahoo-inc.com<mailto:harlowja at yahoo-inc.com>> wrote:
In your proposal does it means that the child process will be restarted (that means kill -9 or sigint??). If so, without taskflow to help (or other solution) that means operations in progress will be corrupted/lost. That seems bad...

A SIGHUP approach could be handled more gracefully (but it does require some changes in the underlying codebase to do this "refresh").


Sent from my really tiny device...

On Dec 15, 2013, at 3:11 AM, "iKhan" <ik.ibadkhan at gmail.com<mailto:ik.ibadkhan at gmail.com>> wrote:

I don't know if this is being planned in Icehouse, if not probably proposing an approach will help. We have seen cinder-volume service initialization part. Similarly if we can get our hands on child process that are running under cinder-volume service, if we terminate those process and restart them along with newly added backends. It might help us achieve the target.


On Sun, Dec 15, 2013 at 12:49 PM, Joshua Harlow <harlowja at yahoo-inc.com<mailto:harlowja at yahoo-inc.com>> wrote:
I don't currently know of a one size fits all solution here. There was talk at the summit of having the cinder app respond to a SIGHUP signal and attempting to reload config on this signal. Dynamic reloading is tricky business (basically u need to unravel anything holding references to the old config values/affected by the old config values).

I would start with a simple trial of this if u want to so it, part if the issue will likely be oslo.config (can that library understand dynamic reloading?) and then cinder drivers themselves (perhaps u need to create a registry of drivers that can dynamically reload on config reloads?). Start out with something simple, isolate the reloading as much as u can to a single area (something like the mentioned registry of objects that can be reloaded when a SIGHUP arrives) and see how it goes.

It does seem like a nice feature if u can get it right :-)

Sent from my really tiny device...

On Dec 13, 2013, at 8:57 PM, "iKhan" <ik.ibadkhan at gmail.com<mailto:ik.ibadkhan at gmail.com>> wrote:

Hi All,

At present cinder driver can be only configured with adding entries in conf file. Once these driver related entries are modified or added in conf file, we need to restart cinder-volume service to validate the conf entries and create a child process that runs in background.

I am thinking of a way to re-initialize or dynamically configure cinder driver. So that I can accept the configuration from user on fly and perform operations. I think solution lies somewhere around "oslo.config.cfg", but I am still unclear about how re-initializing can be achieved.

Let know if anyone here is aware of any approach to re-initialize or dynamically configure a driver.

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Thanks,
IK
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Thanks,
Ibad Khan
9686594607<tel:9686594607>
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--
Thanks,
Ibad Khan
9686594607
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