[OpenAFS] Does vos release/volume replication always initiates data transfer from RW site?

[Jeffrey Altman]

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On 8/6/2018 12:12 PM, Ximeng Guan wrote:
> Indeed if we have two RO replicas at Site B and RW at site A, subsequen=
t release will be twice as consuming, unless "vos release" can be made to=
 be even smarter, such that data is "relayed" among RO sites instead of b=
eing broadcasted from the RW site.
>=20
> I guess that touches some fundamental part of "vos release" which is no=
t trivial: How to optimize the data propagation path for different networ=
k scenarios? How does that affect the integrity among different replicas?=


In OpenAFS, all of the "smarts" are in the vos process.  This process
has no knowledge of the network topology which is why OpenAFS has
difficulties in network environments that lack full end-to-end
connectivity between all peers.

In theory, someone could write a volserver topology map that could be
provided to "vos" as input.  It could be used in conjunction with the
volume site list from the location service to decide how to replicate
the volumes.

The OpenAFS location service doesn't provide clients (cache managers)
any locality information and the Unix cache manager does not rank volume
sites based upon performance characteristics.  How are you ensuring that
clients contact the local fileserver?

Jeffrey Altman


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email;internet:jaltman@auristor.com
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