Running dcc server cluster

Ross West westr@connection.ca
Mon Jun 1 18:56:53 UTC 2009


VS> I hope none of the DCC documentation talks about using a single server-ID
VS> for more than one computer.  Both DCC servers and DCC clients depend
VS> on which DCC server is which by ID.  Things break and alarms go off
VS> when two computers share an ID.

That's what I thought after going through everything.  But the man page
for dccd does talk about a "close cluster of DCC servers" being
identified by a single serverID.  Hence my confusion - thought I was
missing something.

VS>   - Ensure that all of the servers have enough RAM.  You need more than
VS>      3 GByte just for DCC server process and should have more than 4 GByte.
VS>      (That's real memory for a single process and not the kludge that
VS>      lets a 32-bit Intel CPU share more than 4 GBytes among a bunch of
VS>      smaller than 4 GByte processes.)

Gotcha - 64bit OS (not 32bit + PAE).  The memory requirements for a
public server are higher than I was expecting though.  (Was guessing
around 2gig)

As an FYI, in our test environment is using ~150mb per server for a
load of around 200k msgs/day total.

I will say I'm impressed by how much mail DCC sees as mass mail, and
generally how accurate it is.

VS>   - Don't even consider using the 4+ year old version of the DCC source
VS>       distributed by some outfits including Linux repackagers.

Saw that warning - we're running v1.3.103 (Freebsd ports).

VS>   - Define DNS CNAMES for each server, such as dcc1.example.com and
VS>       dcc2.example.com
VS>   - Define DNS A RRs containing IP addresses for all servers, such
VS>       as dcc.example.com.
VS>   - Teach each DCC client about all servers by running
VS>         cdcc "add dcc.example.com RTT-1000 ms  32768 SECRET"
VS>       where SECRET is the password for client-ID 32768 in /var/dcc/ids on
VS>       all servers.  That will let the clients balance their loads among
VS>       the servers named by dcc.example.com.

Already done, although I'm curious if there's a better 'way' of the
two types:

Does defining 2 servers for the dcc client (ie: add dcc1, add dcc2) or
defining 1 server with multiple IP addresses make any difference?

In my testing, I've got 2 servers defined, with 1 having a RTT+500ms
to make a rough 'primary/secondary' kind of setup.

Cheers,
  Ross.

-- 





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