High availability ... again
kbaker at missionvi.com
Wed Jun 23 14:48:03 EDT 2004
This is exactly what I had in mind. Could you maybe give a
quick overview of how you have the replication and
failover setup; specifically "application level
replication vs block"
While the idea of a standby server that uses block level
replication seems very great, if possible I'd like to have
the reliability while still being able to use both
Is it something like this:
- Server A
- active accounts 1-100
- replicate accounts 101-200 from Server B
- Server B
- active accounts 101-200
- replicate accounts 1-100 from Server A
If B goes down, A takes over the accounts it had
replicated from B.
> On Tue, 22 Jun 2004, Etienne Goyer wrote:
>> Does somebody on the list use this solution or a similar
>> one and could
>> comment and the practicality of it ? Perhap M. Carter
>> (if you read the
>> list) could give us a status update for his particuliar
>> project ?
> There's really not a whole lot to say.
> We've been using the code on our main 32k user mail system
> since about
> this time last year for data migration, fast incremental
> backup to a tape
> spooling system, and rolling replication for live updates.
> We also used
> the replication system to migrate from a UW based system
> to Cyrus.
> We have 16 small Linux servers running as 8 pairs. All the
> systems are
> live Cyrus servers, half the accounts on each system are
> replica versions.
> One of the 16 had a hardware fault a couple of weeks back
> and noone has
> moaned at me after we switched to the replica which is
> always a good sign.
> From my perspective the advantage of application level
> replication over
> block level replication like DRDB is flexibility.
> Read/write access to
> both master and replica systems can be useful: we maintain
> of MD5 checksums for all the messages and cache entries on
> each server.
> Its also rather cute to run PINE against both master and
> replica version
> of a given mailbox and watch the replica play follow my
> leader :).
> David Carter Email:
> David.Carter at ucs.cam.ac.uk
> University Computing Service, Phone: (01223)
> New Museums Site, Pembroke Street, Fax: (01223)
> Cambridge UK. CB2 3QH.
> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
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