[Gluster-users] NFS availability

[Jeff Darcy]

On 01/31/2013 01:59 PM, Stephan von Krawczynski wrote:
> You don't want to use DNS in an environment where security is your first rule.
> If your DNS drops dead your setup is dead. Not very promising ...
> The basic goal of glusterfs has been to secure data by replicating it.
> Data distribution is really not interesting for us. Now you say "go and
> replicate your data for security, but use DNS to secure your setup".
> ???
> You really seem to like Domino-setups. DNS dead => everything dead.

This vulnerability can be reduced by using multiple DNS servers, and 
even further by using local caches/proxies which can still do 
round-robin for you.  There have also been solutions mentioned that 
don't rely on DNS, so talking about DNS unreliability is a total red 
herring.

>>    * The mount option backupvolfile-server. An fstab entry like
>>      "server1:myvol /mnt/myvol glusterfs backupvolfile-server=server2 0
>>      0" will allow the mount command to try server2 if server1 does not
>>      mount successfully.
>
> And how many backup servers do you want to name in your fstab? In fact you
> have to name all your servers because else there will always be at least one
> situation you are busted.

There is *always* at least one situation, however unlikely, where you're 
busted.  Designing reliable systems is always about probabilities.  If 
none of the solutions mentioned so far suffice for you, there are still 
others that don't involve sacrificing the advantages of dynamic 
configuration.  If your network is so FUBAR that you have trouble 
reaching any server to fetch a volfile, then it probably wouldn't do you 
any good to have one locally because you wouldn't be able to reach those 
servers for I/O anyway.  You'd be just asking for split brain and other 
problems.  Redesigning the mount is likely to yield less benefit than 
redesigning the network that's susceptible to such failures.