[Linux-cluster] Home-brew SAN/iSCSI

[Madison Kelly]

Mike Cardwell wrote:
> Madison Kelly wrote:
> 
>>   Until now, I've been building 2-node clusters using DRBD+LVM for the 
>> shared storage. I've been teaching myself clustering, so I don't have 
>> a world of capital to sink into hardware at the moment. I would like 
>> to start getting some experience with 3+ nodes using a central SAN disk.
>>
>>   So I've been pricing out the minimal hardware for a four-node 
>> cluster and have something to start with. My current hiccup though is 
>> the SAN side. I've searched around, but have not been able to get a 
>> clear answer.
>>
>>   Is it possible to build a host machine (CentOS/Debian) to have a 
>> simple MD device and make it available to the cluster nodes as an 
>> iSCSI/SAN device? Being a learning exercise, I am not too worried 
>> about speed or redundancy (beyond testing failure types and recovery).
> 
> Yeah, that's possible. Just use iscsid to export the device. If this is 
> just for testing/learning purposes have you considered using virtual 
> machines to minimise the hardware footprint? You could have a single 
> host machine that acts as the SAN, exporting a device using iscsid and 
> three vm's running on top of VMWare server on the same machine which 
> make up the cluster...

Thanks! I was thinking that was what I could do, but I wanted to ask 
before sinking a lot of time/money just to find out I was wrong. :)

I thought about Xen VMs. I'll have to see if I can simulate things like 
fence devices and such. Though, as good as virtualization is, I wonder 
how close I could get to simulating real world? When I run into 
problems, it would be another layer to wonder about. However, there is 
no denying the cost savings! I will look into that more.

Madi