[Gluster-users] [DHT] The myth of two hops for linkto file resolution

Pranith Kumar Karampuri pkarampu at redhat.com
Thu May 4 10:33:18 UTC 2017


On Sun, Apr 30, 2017 at 9:33 AM, Raghavendra Gowdappa <rgowdapp at redhat.com>
wrote:

> All,
>
> Its a common perception that the resolution of a file having linkto file
> on the hashed-subvol requires two hops:
>
> 1. client to hashed-subvol.
> 2. client to the subvol where file actually resides.
>
> While it is true that a fresh lookup behaves this way, the other fact that
> get's ignored is that fresh lookups on files are almost always prevented by
> readdirplus. Since readdirplus picks the dentry from the subvolume where
> actual file (data-file) resides, the two hop cost is most likely never
> witnessed by the application.
>
> A word of caution is that I've not done any testing to prove this
> observation :).
>

May be you should do it and send an update. That way we can use the
knowledge to do something.


>
> regards,
> Raghavendra
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> Gluster-users at gluster.org
> http://lists.gluster.org/mailman/listinfo/gluster-users
>



-- 
Pranith
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