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3 server requirement?


cwhitmore
3 Posts
September 8, 2017, 1:49 am

In your video you said that three petasan servers are required. If I'm running 2 hyperV 2012 R2 hosts in a cluster do I really need three petasan servers on the backend?

#1

hoanglongvina
12 Posts
September 8, 2017, 4:09 am

Hi cwhitmore,

You need at least 3 server petasan. petasan using ubuntu core 16.04

diagrams:

#2

admin
2,845 Posts
September 8, 2017, 8:59 am

The min of 3 requirement is from underlying systems like Ceph and Consul that require odd number of servers to achieve quorum and avoid split brain conditions.

In PetaSAN it is possible to create one of these machines with only management role and un-check the storage and iSCSI roles. In such case it will not require a lot of resources and can be run as a vm in one of your 2 hyper-vs, it will take part in quorum elections. The remaining 2 PetaSAN nodes will be more powerful bare metal machines housing the storage.

#3

cwhitmore
3 Posts
September 8, 2017, 4:38 pm

Thanks for the responses. If I setup the third PetaSAN as a VM on Hyper-V what do the specs need to be?

#4

admin
2,845 Posts
September 8, 2017, 5:16 pm

2G RAM /50GB disk.

For network: it should have the same number of interfaces as your real nodes and be able to connect with them via the management/subnet1/subnet2

#5

cwhitmore
3 Posts
September 11, 2017, 1:48 pm

Can the third PetaSAN run off of it's own storage? (ex: If Hyper-V hosts are using PetaSAN for storage and the PetaSAN running as a VM boots up does it have to use different storage than what's provided by the two other PetaSAN's?.)

 

#6

admin
2,845 Posts
September 11, 2017, 4:25 pm

The third node should run off its own storage...like using local file on the hyper-v,  in fact all PetaSAN nodes run using local storage.

The other hyper-v vms should be stored on the PetaSAN iSCSI disk to provide high availability if the hyprr-v fails. But the third PetaSAN does not need this since it already has HA built in by Ceph.

#7