Hi Jerome,
On Tue, Feb 22, 2005 at 09:11:26PM -0500, Jerome LAURET wrote:
> So, we started xrootd and olbd on 190 nodes with one
> redirector (+olbd -m) and of course, bumped into the 64 connection
> limit for olbd. We now have questions:
>
> - Is there a way to circunvent the 64 connection limit via a
> parameter of some kind we may have missed ??
No, there is no parameter to do this.
> - If a redirector + olbd manager can connect to only 64 nodes,
> what would happen to the "rest" of the nodes in our configuration
> i.e. the 190-64 other nodes ??
IIRC, they don't succeed in subscribing to the redirector (with messages
in all log files) and thus don't succeed in serving data.
> * Does this implie that the redirector cannot do load balancing
> with those nodes ??
With the existing olbd structure, you would have to create a hierarchy
of redirectors, each with a group of 64 data servers. (But see below.)
> * Does it mean that a single redirector cannot handle more
> than 64 nodes and their files ??
At the moment you can build a hierarchy where each group of 64 has
a redirector and then those subscriber to a meta-redirector. What Andy
has been adding lately is something that avoids you have to specify all
of that configuration in a hardcoded way, by allowing the machines
to self-configure. (As I understand it you basically just configure all of the
data servers _and_ at least 1 redirector per 64 dataservers to connect
to the main redirector and they self-configure into a hierachical system.)
Andy should comment on when he thinks a test version of this might be
ready...
> * If I use DNS RR, what happens then ?? Does every redirector
> gets a set of 64 nodes ?? Does the redirector exchange information
> about each other's known files (and node/load selection) ??
At SLAC their are two redirectors which are DNS aliased to the same
address, but this is done simply for redundancy, not to create this
type of hierachy.
Probably the best bet is for you to use this self-organizing servers
feature which Andy has been building. (I also wanted to do some testing
of that.) I didn't realize that you had so many servers. Or are these
the worker nodes you are trying to allow to serve data from their local
disks?
(I was travelling and thus still need to catch up on various postings to
this list from the last 4-5 days. Expect additional response over the next
day or so as I read all of that!)
Pete
> In case this is needed, our configuration is as described
> by a previous Email by Pavel in
> http://www.slac.stanford.edu/cgi-bin/lwgate/XROOTD-L/archives/xrootd-l.200502/date/article-55.html
>
>
>
> --
> ,,,,,
> ( o o )
> --m---U---m--
> Jerome
>
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Peter Elmer E-mail: [log in to unmask] Phone: +41 (22) 767-4644
Address: CERN Division PPE, Bat. 32 2C-14, CH-1211 Geneva 23, Switzerland
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