Re: Funding Cyrus High Availability

From: David Lang (no email)
Date: Sun Sep 19 2004 - 19:54:50 EDT


please don't misunderstand my posts. it's not that I don't think that
active/active/active is possible, it's just that I think it's far more
complicated.

assiming that the simplest method would cost ~$3000 to code I would make a
wild guess that the ballpark figures would be

1. active/passive without automatic failover $3k

2. active/passive with automatic failover (limited to two nodes or withing
a murder cluster) $4k

3. active/passive with updates pushed to the master $5k

4. #3 with auto failover (failover not limited to two nodes or a single
murder cluster) $7k

5. active/active (limited to a single geographic location) $10k

6. active/active/active (no limits) $30k

in addition to automaticly re-merge things after a split-brin has happened
would probably be another $5k

now this doesn't mean that all ofs must be done in this funded project. I
believe that people would end up going from #1 or #3 to #2 or #4 by
individuals coding the required pieces and sharing them (#4 has as much of
a jump over #3 becouse of all the different senrios that are involved,
each one is individually simple) however #5 and #6 are significantly more
difficult and I would not expent them to just happen (they are also much
more intrusinve to the code so there is some possibility of them not
getting merged into the core code quickly)

David Lang

-- There are two ways of constructing a software design. One way is to
make it so simple that there are obviously no deficiencies. And the other
way is to make it so complicated that there are no obvious deficiencies.
  -- C.A.R. Hoare

P.S. #1-4 all could qualify as the first way, #5 and #6 are both
complicated enough to start with that it is really hard to keep them out
of the second way

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