[Gluster-devel] Quota-2

[Vijaikumar Mallikarjuna]

On Fri, Dec 18, 2015 at 8:28 PM, Shyam <srangana at redhat.com> wrote:

> <first off the cuff response>
>
> On 12/18/2015 04:00 AM, Vijaikumar Mallikarjuna wrote:
>
>> Hi All,
>>
>> Here is the summary of discussion we had today on Quota-v2
>>
>> Project, user and group quotas will use the same logic of accounting the
>> usage
>>
>> Quota-v2 should be compatible with both DHT-v1 and DHT-v2
>>
>> Project quotas will use gfid of the given path as the project-id.
>>      each inode will have a associated project-id which needs to be
>> embedded within inode.
>>      when creating new file, it will inherit project-id from its parent
>> inode.
>>      In case if parent inode doesn't contain project-id, then there
>> should be a mechanism to
>>      find the project-id given a gfid, so back-pointers can solve this
>> problem
>>
>
> Why would the parent not contain a project-id? and if it does not contain
> a project-id, why would you need to find a project-id?
>
> What I can visualize is that, the parent is not yet part of a quota
> project, hence it does not contain a project-id. When this becomes a part
> of some quota restriction it would start getting a quota. This seems to be
> one case where the project-id would be missing, but by choice.
>
> What am I missing here?
>
> There are two scenarios where project-id can be missing
1) When quota is enabled on a pre-existing data,
2) Directory created when one of the brick is down

Thanks,
Vijay


>      which xlator DHT/marker will set the project-id in the inode? this
>> needs to be decided
>> User and group quotas will use uid and gid to account the usage
>>
>> Quota has below set of operation which should be performed as a single
>> transaction
>>        read current size
>>        read current contribution
>>        update delta to the contribution
>>        update size to user/project inode
>> In the current directory quota, to make this transaction crash
>> consistent we use a mechanism of setting dirty flag in a parent inode.
>> This mechanism will not work efficiently with project quotas. Journaling
>> will be the good solution for crash-consistency.
>>
>> Quota 2 depends on:
>>        back-pointers: to find project-id from gfid
>>        journaling: for crash consistency of accounting
>>
>>
>> Thanks,
>> Vijay
>>
>
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