[Spread-users] spread daemon
Ryan Caudy
caudy at jhu.edu
Thu May 15 11:04:37 EDT 2003
The difference is in how the communication takes place. Clients on the
same host as their daemon can communicate with it using Unix domain
sockets (IPC); otherwise they use TCP. Daemons communicate with other
daemons over multicast/broadcast channels if possible (unicast if that
fails) using UDP. So, if you run four daemons, transmissions will only
need to go on the network once (plus or minus some amount of traffic for
reliability and ordering). If you run one daemon, it will receive each
message from a client via unicast, and send it out to each client via
unicast; for the remote clients, this will be over TCP. The data will
be transferred over the network something like n times, where n is the
number of clients (with some additional traffic caused by TCP reliability).
The other issue is that, with a spread cluster of four daemons, the
behavior of spread when experiencing network/host faults is more
meaningful. With only one daemon, there can be at most one partition of
the spread network.
--Ryan
Cédric Coulon wrote:
>Hi,
>
>I use spread in a cluster of PC with 4 nodes.
>I would know the differences beetwen launching a spread's daemon on each
>node and only one spread's daemon on one node?
>
>Thanks.
>
>----
>Cédric Coulon Tel: 02 51 12 59 63
>IRIN, 2, rue de la Houssiniere, BP 92208 Fax: 02 51 12 58 12
>44322 NANTES cedex 3
>FRANCE mailto:Cedric.Coulon at irin.univ-nantes.fr
>
>
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