[Gluster-devel] Need help with bitrot

[FNU Raghavendra Manjunath]

As of now, signing happens only upon data modification. Metadata changes
and xattr changes does not trigger signing.

For more information about gluster and its internals, you can look here "
https://gluster.readthedocs.org/en/latest/".

Regards,
Raghavendra

On Thu, Feb 25, 2016 at 10:28 AM, Ajil Abraham <ajil95.abraham at gmail.com>
wrote:

> Thanks FNU Raghavendra.  Does the signing happen only when the file data
> changes or even when extended attribute changes?
>
> I am also trying to understand the Gluster internal data structures. Are
> there any materials for the same? Similarly for the translators, the way
> they are stacked on client & server side, how control flows between them.
> Can somebody please help?
>
> - Ajil
>
>
> On Thu, Feb 25, 2016 at 7:27 AM, FNU Raghavendra Manjunath <
> rabhat at redhat.com> wrote:
>
>> Hi Ajil,
>>
>> Expiry policy tells the signer (Bit-rot Daemon) to wait for a specific
>> period of time before signing a object.
>>
>> Whenever a object is modified, a notification is sent to the signer by
>> brick process (bit-rot-stub xlator sitting in the I/O path) upon getting a
>> release (i.e. when all the fds of that object are closed). The expiry
>> policy tells the signer to wait for some time (by default its 120 seconds)
>> before signing that object. It is done because, suppose the signer starts
>> signing (i.e. read the object + calculate the checksum + store the
>> checksum) a object the object gets modified again, then a new notification
>> has to be sent and again signer has to sign the object by calculating the
>> checksum. Whereas if the signer waits for some time and receives a new
>> notification on the same object when its waiting, then it can avoid signing
>> for the first notification.
>>
>> Venky, do you want to add anything more?
>>
>> Regards,
>> Raghavendra
>>
>>
>>
>> On Wed, Feb 24, 2016 at 12:28 AM, Ajil Abraham <ajil95.abraham at gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> I am a student interested in GlusterFS.  Trying to understand the design
>>> of GlusterFS. Came across the Bitrot design document in Google. There is a
>>> mention of expiry policy used to sign the files. I did not clearly
>>> understand what the expiry policy is.  Can somebody please help?
>>>
>>> -Ajil
>>>
>>> _______________________________________________
>>> Gluster-devel mailing list
>>> Gluster-devel at gluster.org
>>> http://www.gluster.org/mailman/listinfo/gluster-devel
>>>
>>
>>
>
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