High availability ... again

[Kevin Baker]

Thanks...


I'm familiar with what it is... I'm not familiar with how
to setup application level replication with Cyrus.
MySQL/LDAP NP...

I've looked through the docs/archives and haven't found
anything... Murder seems more focused on partitioning.






>
>
> --On Wednesday, June 23, 2004 11:48 -0700 Kevin Baker
> <kbaker at missionvi.com> wrote:
>
>> David,
>>
>> 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"
>
> application lvel means exactly that.  The actual
> program/server software
> involved does it's own replication.  Like Oracle RAC or
> MySQL replication.
> block level means soemthing at the disk I/O layer does it
> all, without the
> app's knowledge.
>
>>
>> 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
>> machines.
>>
>> 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.
>>
>>
>> Thanks,
>>
>>
>>
>>
>>
>>
>>> 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
>>> databases
>>> 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)
>>> 334502
>>> New Museums Site, Pembroke Street,       Fax:   (01223)
>>> 334679
>>> Cambridge UK. CB2 3QH.
>>> ---
>>> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
>>> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
>>> List Archives/Info:
>>> http://asg.web.cmu.edu/cyrus/mailing-list.html
>>>
>>
>> ---
>> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
>> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
>> List Archives/Info:
>> http://asg.web.cmu.edu/cyrus/mailing-list.html
>>
>
>
>
> --
> Undocumented Features quote of the moment...
> "It's not the one bullet with your name on it that you
> have to worry about; it's the twenty thousand-odd rounds
> labeled `occupant.'"
>    --Murphy's Laws of Combat
>
> ---
> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
> List Archives/Info:
> http://asg.web.cmu.edu/cyrus/mailing-list.html
>

---
Cyrus Home Page: http://asg.web.cmu.edu/cyrus
Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html