[ovirt-devel] Storage in VDSM questions

[Shmuel Melamud]

Hi!

On Thu, Jun 23, 2016 at 9:51 AM, Liron Aravot <laravot at redhat.com> wrote:

>
> 3. What hsm.spmSchedule() method does?
>>
> Schedules a task to be executed as SPM (used to perform operation that
> alter
> the shared storage or data operations currently).
>

​But SPM is a particular host.​ What does this method do, if it is called
not on SPM host? Returns error? Or somehow transfers the task to the SPM
host?



> 7. Why in HSM we are using vars.task.getSharedLock(STORAGE, sdUUID)
>> sometimes instead of domain lock?
>>
> The task lock (which uses the resource manager) is used to acquire in
> memory logical lock within the current host.
> Theoretical example- you wouldn't want to attempt to delete a domain while
> you create a volume on it.
>

​But this lock works only inside the host. So, if some other host will try
to create a volume, this lock will not help. So what's​

11. What methods dom.linkBCImage(imgPath, imgUUID) and
> dom.unlinkBCImage(imgUUID) do?
>
Creates/Removes a symlink to a given image.

​Where this symlink is located? What is its purpose?​

​​

> ​
> ​
> ​
> ​> ​
> 12. What methods dom.activateVolumes(imgUUID, imgVolumes) and
> dom.deactivateImage(imgUUID) do?
>
> ​
​
​
Can you be a bit more specific in the question? I don't have much to add
> ​
​
​
over the method names.

​I understand that it activates/deactivates volumes. But what does it mean?
What is an "active" volume and how does it differ from "inactive"?​

​Shmuel​
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