Re: ceph-disk pyudev implementation

[Loic Dachary <loic@dachary.org>]

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Hi,

The approach you describe makes sense to me. And you've done a nice job with the refactor.

I'm not familiar with pyudev though and other Ceph developers may already have an opinion (or answers). When adding new dependencies to Ceph, I think we need to assert how stable / reliable those dependencies are. How well tested do you think it is ? https://github.com/pyudev/pyudev/blob/master/Vagrantfile suggests there are tests with good coverage, https://github.com/pyudev/pyudev/pulls and https://github.com/pyudev/pyudev/issues?q=is%3Aopen+is%3Aissue have few open issues and a number of resolved ones. The timeline is a bit strange : a burst of recent commits and a large gap back to 2012. But maybe it's widely used and this really is not a concern ? 

Is there a particular reason why you did not re-use the json format for ceph-disk list ?

Could you make your new ceph-disk into a pull request so that it can run integration tests ?

Cheers

On 09/09/2015 08:52, Chaitanya Huilgol wrote:
> Hi Loic,
> 
> As discussed in the multipath tracker, please find the port of ceph-disk which is based on pyudev (https://pyudev.readthedocs.org/en/latest/  python libudev binding)
> 
> Here is a short summary on the approach:
> - Current ceph-disk determines various properties on block device by path string manipulations and /sys/dev properties
> - These are difficult to implement and fragile for device types such as DM multipath.
> - Since different code needs to be added based on the device type, a Block device class based approach has been used.
> - Based on the device type supplied a block device object is instantiated (currently GenericBlockDev or DMBlockDev).
> - Each class implements device specific functionality as an implementation of the abstract BlockDevBase base class.
>         a. Get partition device from base device
>         b. Get base device from partition
>         c. Get Part UUID and Type
>         d. Determine if device path is partition
>         e. Determine if device is referenced
>          f. Get HW sector size
>         g. List partitions
> 
> In Prepare/Activate/List code paths, the required device object is instantiated and hence these code paths remain clean
> 
> This port also support multipath devices with the DMBlockDev Class.
> 
> https://github.com/chaitanyahuilgol/ceph-disk-udev.git
> 
> Let us know your thoughts.
> 
> Regards,
> Chaitanya
> 
> 
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-- 
Loïc Dachary, Artisan Logiciel Libre


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