topic Re: Adding to P4500 in StoreVirtual Storage

Adding to P4500

danletkeman — Tue, 17 Apr 2012 16:46:40 GMT

Hello,

We currently have a P4500 2 node san. We are looking at adding to it, but I am unsure if I can add one more node to a two node system, or do I have to add 2 nodes to the existing 2 node system?

Thanks,

Dan.

Re: Adding to P4500

giladzzz — Tue, 17 Apr 2012 17:22:57 GMT

There is no problem adding one more node to a two node cluster

make sure it's the same capacity other wise if it has more capacity you will loose

disk space. Also if you have a 3 node cluster you don't need to use FOM.

Regards

Re: Adding to P4500

danletkeman — Tue, 17 Apr 2012 17:54:09 GMT

Thanks for the quick reply.

If I have a three node cluster is network raid 5 something that is recommended or will I loose performance over the mirrored system that I have now?

Thanks,

Dan.

Re: Adding to P4500

giladzzz — Tue, 17 Apr 2012 18:07:38 GMT

You can use raid 5 on a 3 node cluster i am not sure about performance

take in to account that once you add the third node your

raid 10 disks will be re-distribute on all 3 nodes.

and then you can change from network raid 10 to 5

it's an online process.

Re: Adding to P4500

Bryan McMullan — Tue, 17 Apr 2012 18:11:21 GMT

Overall, you will lose IOPS using network RAID 5 over network RAID-10.

In the past, I stayed away from NWR5 as the performance drop wasn't worth the additional capacity. Though HP did make improvements in 9.5 they say making it closer to being on-par with NWR10. Try adding a volume using 5 and see if the performance is up to your needs. You can mix and match the network raid levels throughout your volumes.

Re: Adding to P4500

oikjn — Wed, 18 Apr 2012 13:15:40 GMT

all that said, it is simple to just add a single additional node to the 2-node cluster and keep network raid10. You will gain additional stoage space which should be equal to about 1/2 of the raw storage capacity of the node. Adding a third node has a bunch of benefits... it adds to capacity, adds to IOPs and lets you run without the need for a FOM. Just make sure the node is the same as the other nodes or adding it can result in a net performance loss if the node is slower since performance is based off of the slowest node.

Re: Adding to P4500

Steve Burkett — Thu, 19 Apr 2012 12:55:52 GMT

You also want to consider SANiQ version numbers. You'll probably get SANiQ 9.5 pre-loaded on the new node, you need to be on at least version 8.5 to be able to add a 9.5 node in to your existing cluster.

And make sure all the firmwares are up to date on it before you add it, including the SAS backplane and drive firmware.