[Gluster-devel] [Gluster-users] gfid generation

[Ankireddypalle Reddy]

Kaushal/Pranith,
                                  Thanks for clarifying this. As I understand there are 2 id's. Please correct if there is a mistake in my assumptions:
                                  1) HASH generated by DHT and this will generate the same id for a given file all the time.
                                  2) GFID which is an version 4 UUID. As per the below links this is supposed to contain a time stamp field in it.  So this will not generate the same id for a given file all the time.
                                       https://en.wikipedia.org/wiki/Universally_unique_identifier
                                       https://tools.ietf.org/html/rfc4122
 
Thanks and Regards,
ram
-----Original Message-----
From: Kaushal M [mailto:kshlmster at gmail.com] 
Sent: Tuesday, November 15, 2016 1:21 PM
To: Ankireddypalle Reddy
Cc: Pranith Kumar Karampuri; gluster-users at gluster.org; Gluster Devel
Subject: Re: [Gluster-users] gfid generation

On Tue, Nov 15, 2016 at 11:33 PM, Ankireddypalle Reddy <areddy at commvault.com> wrote:
> Pranith,
>
>                  Thanks for getting back on this. I am trying to see 
> how gfid can be generated programmatically. Given a file name how do 
> we generate gfid for it. I was reading some of the email threads about 
> it where it was mentioned that gfid is generated based upon parent 
> directory gfid and the file name. Given a same parent gfid and file 
> name do we always end up with the same gfid.

You're probably confusing the hash as generated for the elastic hash algorithm in DHT, with UUID. That is a combination of

I always thought that the GFID was a UUID, which was randomly generated. (The random UUID might be being modified a little to allow some leeway with directory listing, IIRC).

Adding gluster-devel to get more eyes on this.

>
>
>
> Thanks and Regards,
>
> ram
>
>
>
> From: Pranith Kumar Karampuri [mailto:pkarampu at redhat.com]
> Sent: Tuesday, November 15, 2016 12:58 PM
> To: Ankireddypalle Reddy
> Cc: gluster-users at gluster.org
> Subject: Re: [Gluster-users] gfid generation
>
>
>
> Sorry, didn't understand the question. Are you saying give a file on 
> gluster how to get gfid of the file?
>
> #getfattr -d -m. -e hex /path/to/file shows it
>
>
>
> On Fri, Nov 11, 2016 at 9:47 PM, Ankireddypalle Reddy 
> <areddy at commvault.com>
> wrote:
>
> Hi,
>
>         Is the mapping from file name to gfid an idempotent operation.  
> If so please point me to the function that does this.
>
>
>
> Thanks and Regards,
>
> Ram
>
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> Pranith
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