Information regarding setting up a cluster using shared storage.

donkeh

New Member
Jan 25, 2013
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Hi,

Let me start by saying I have read through this thread which gives some very useful information, but I am still left with some unanswered questions which I hope you can help with.

I have 3 physical machines at the moment, 2 running proxmox 2.2 and one machine running freenas.

I setup the first proxmox host, configured an iscsi target (freenas) and created LVM based on the iscsi target.

I then added created a cluster on the first host and added the second host to this cluster.

This immediately brought the iscsi target and LVM target to the second host also.

I was able to choose migrate on one of the VM's running on node 1, migrate it to node 2 and it was practically instant - due to the storage of the VM on the freenas device.

My outstanding questions are these...

1. I read in the above mentioned thread about problems with 2 nodes connecting to one iscsi/lvm target. Have I done something wrong therefore in what I just did ?

2. I understand the ability to migrate a VM. What happens if I lose node 1, which was running VM1 for example. Can I now bring that online on node2 because it is stored on the network storage?

Thanks,

Leon
 
a couple of bits of advice ive picked up from reading the forum:

freenas - use something else as loads of people have said there are issues with the iSCSI...

2 nodes - although its supported, its not recommended - use 3 its more reliable for quorum.

Question 1: Nope. thats how my two clusters are configured.

Question 2: Yes. you will need to change some config on the servers but ultimately yes.
 
a couple of bits of advice ive picked up from reading the forum:

freenas - use something else as loads of people have said there are issues with the iSCSI...

2 nodes - although its supported, its not recommended - use 3 its more reliable for quorum.

Question 1: Nope. thats how my two clusters are configured.

Question 2: Yes. you will need to change some config on the servers but ultimately yes.

Thanks for your thoughts. I have read some people complaining about freenas, but as yet I have not seen any problem with it - do you have any specific details ?

At the moment, I am evaluating proxmox however, and all is in a test environment. Openfiler seems to have been suggested also.

With regards the questions...

1. Good to know the same for you.

2. Again, good to know it is possible - but do you have any links to any further information/documentation about it ?

Thanks,

Leon
 
2. Again, good to know it is possible - but do you have any links to any further information/documentation about it ?

all i can remember now is that you ahve to change something like pvexpected=1 or something in cluster config file and it allows you read/write access to the cluster information AFAIK all vm info is stored on a replicated file system between all the nodes in a cluster - the only thing that is stored on each server is memory and cpu operation.

Ive never tried it so couldnt give any info on it although i have seen a number of posts about it.
 
Thanks for your thoughts. I have read some people complaining about freenas, but as yet I have not seen any problem with it - do you have any specific details ?

At the moment, I am evaluating proxmox however, and all is in a test environment. Openfiler seems to have been suggested also.

With regards the questions...

1. Good to know the same for you.

2. Again, good to know it is possible - but do you have any links to any further information/documentation about it ?

Thanks,

Leon
Hi,
access from different nodes to one lvm isn't a problem with pve - pve use an internal locking.
For iSCSI - perhaps you could also try http://www.openattic.org/ - work without trouble for me on a test-system.
About 2-node-cluster: If one node fail, you lost the quorum an can't activate an VM from the failed node on the running node (/etc/pve is write protected).
After manual get quorum "pvecm expected 1" - see "man pvecm" you can move the VM-config to the running node and start the VM again.

Udo
 
Thanks Udo,

I have no time to test/play for a couple of days - but will report back.

Leon