[OpenAFS] drbd or nbd with openafs?

[Paul Blackburn]

Hello Töns,

If you want to improve the availability of your AFS database service
for your AFS cell, you simply have multiple db servers.

Data is "cloned" between the db servers using UBIK.
If one db server fails, the others keep serving data.

Multiple database servers also distributes the processing load
from clients accessing database servers: it scales.

It works beautifully.

AFS database servers do not have to be "seriously chunky" machines.
It is possible to use fairly basic PC hardware running, say, Linux.
This means it is cheap and you can have lots of db servers
which give your users a reliable highly-available AFS service.

We use dedicated (eg database server only) machines in one of our cells.
This makes it easy to upgrade one db server without major impact on the 
live service.
Repeat this and you can easily upgrade/re-install each db server in turn
with very little disruption to AFS clients.

HTH.
--
cheers
paul                             http://acm.org/~mpb



Derek Atkins wrote:

>I presume the idea is to be able to failover to a second machine which
>would take over the IP address of the first.  Fileserver state isn't
>stored in /usr/afs/db, it's stored in core.  This includes all the RX
>connection state, callback state, etc.  This information is not stored
>on disk, so there is nothing to mirror.
>
>-derek
>
>Nathan Rawling <nrawling@firedrake.net> writes:
>
>  
>
>>Okay, it pains me to say this, but...
>>
>>Couldn't you also mirror /usr/afs/db?
>>
>>Nathan
>>
>>On Fri, 20 Jun 2003, Derek Atkins wrote:
>>
>>    
>>
>>>Yes, it would successfully mirror the file system data, but not
>>>necessarily the fileserver "state".  It would not allow for
>>>easy fileserver failover.
>>>
>>>-derek
>>>
>>>Toens Bueker <toens.bueker@gmx.net> writes:
>>>
>>>      
>>>
>>>>Hi *,
>>>>
>>>>would it be possible to use drbd
>>>>(http://www.complang.tuwien.ac.at/reisner/drbd/) or nbd
>>>>(http://www.it.uc3m.es/~ptb/nbd/) - block device
>>>>mirroring over ip - on Linux servers in order to mirror
>>>>vice-partitions for ha-configurations?
>>>>
>>>>Anybody doing this already? Any hints?
>>>>
>>>>by
>>>>Töns
>>>>--
>>>>There is no safe distance.
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>>>>        
>>>>
>>>      
>>>
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>>
>
>  
>