[OpenAFS] Backup Server for down time

[Jason Edgecombe]

Lars Wilke wrote:
> * Ali wrote:
>   
>>    Can open-afs act as a backup server for me on another
>>    computer so that if my main afs server goes down
>>     the backup one does exactly what it was doing ?
>>    If yes, Will it synchronize automatically data when it starts up?
>>     
>
> AFS Replication is read only, a little bit like with mysql. But you have to
> take manual snapshots (unlike mysql) and you have to manually convert these
> to RW Volumes. Without that the snapshots are read only.
> You would either have to do it by hand or setup heartbeat or something like that.
> Hm, not sure if it would be possible to use shared storage for the fileservers
> and have two fileservers attached to the storage in an active-passive setup.
>
> The Kerberos stuff is another thing, at least MIT and Heimdal allow a master-
> slave setup, where changes to the master are replicated to the slave.
>
> http://www.dementia.org/twiki/bin/view/AFSLore/GeneralFAQ#1_05_f_Replicated_AFS_volumes
> The FAQ is in some points a little bit outdated.
> But the mailinglist archive will hold more detailed answers i guess :)
>
> cheers
>
>    --lars
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>   
Aside form fileservers, your Kerberos server can be set up in a 
master/slave failover. AFS also had Cell or DB servers which host the 
volume and users databases. The recommended number of Cell servers is 
three. With three cell servers, you have replication of the databases 
with automatic failover and re-syncing when the problem server comes 
back online.

As Lars wrote, file server replication is strictly read-only with 
triggered updates, but you can have different directories hosted on 
different servers to reduce the impact of one server going down.

Jason