Re: server unavailable in proxy backends

[Quanah Gibson-Mount <quanah@stanford.edu>]

--On Friday, May 05, 2006 5:37 PM -0400 Aaron Richton 
<richton@nbcs.rutgers.edu> wrote:

> > ldap-mail1: ldap1 (1), ldap2 (10), ldap3 (100), ldap4 (1000), ldap7
> > (1000) ldap-mail2: ldap2 (1), ldap3 (10), ldap1 (100), ldap5 (1000),
> > ldap8 (1000) ldap-mail3: ldap3 (1), ldap1 (10), ldap2 (100), ldap6
> > (1000), ldap9 (1000)
>
> This sounds like DNS load balancing. Consider when ldap{1,2,3,4,7} are
> down, and therefore your entire ldap-mail1 DNS alias is toast, you still
> need an algorithm to drop down to ldap-mail2--which I interpreted as the
> question at hand, and (I think, but please point out flaws) could be
> addressed at the application level by any of the responses on this thread.

Yes, it is DNS load balancing, and was purely an example of what could be 
done.

For example, all the ldap servers could have been listed in a given 
ldap-mail* name, with various weights, and assuming I had some offsite 
servers (which I am supposed to soon), then they could also be in the pool 
at very high weights (say 50000), which generally would mean they'd only 
get sent back if they were the only ones in the pool.

Part of what is happening here, which I don't think I made clear, is that 
membership in the pool is controlled by a client on the ldap server.  If a 
given ldap server (or set of ldap servers) drops into a crack opened up by 
an earthquake, they are no longer listed as part of the pool.


;)

--Quanah

--
Quanah Gibson-Mount
Principal Software Developer
ITS/Shared Application Services
Stanford University
GnuPG Public Key: http://www.stanford.edu/~quanah/pgp.html