RAID Recommendation

Hi!

I am just starting with the setup for my first centrals NAS / SAN combination. Open-E is running and the first basic config has been done. My controller is a 3ware 9650 with 8 pieces of 500 GB SATA 24/7 Barracuda hard disks from Seagate. I do not need so much space so I decided to configure RAID-10 for speed and security resulting in 2 TB usable storage space.

I will use the first TB for NAS storage which will be used from up to 10 clients. In the second TB I will create an iSCSI volume, which will be used from 3 ESXi hosts for VMFS storage of about 5 VMs (mixed VMs of database, mail server and so on).

Now here is my question:
How do I setup the RAID? Do I create 2 arrays of 4 disks each, one for iSCSI and the other one for NAS?
Or do I get even better speed, when I create one big arrax with 8 disks, where I will create a share on and an iSCSI volume?

I searched a lot on google for recommendations about RAID, but I found nothing that fits my question..

I think in your case with only 8 spindles would be better then breaking them into 2 smaller arrays. If you had 14 spindles then I would use 2 RAID 10's.

Some information that I found to be useful.

http://searchstorage.techtarget.com/...463996,00.html


here's the thing to do for good I/O performance:

1) Use a LOT of spindles. If you go to http://www.tpc.org
and look at the specs on the designs to achieve maximum database
performance, you'll notice they use hundreds of drives. By a lot of
spindles I do not mean large RAID sets. You should concatenate many
smaller RAID sets into a single LUN either by using host software or LUN
virtualization within the storage hardware, if it has that capability..........

i myself wouldnt go with raid10 on all 8 disks, no hotspare, most propably all disks are of the same production series, in worst case with 'just' 2 failing disks you are going to lose all your data

if you need speed think about going with raid10 from 6disks and 2hotspares, or if safety is more important then raid6 with 7disks and 1hotspare

I've never liked the idea of a hot spare, I've lost a 4TB raid to the gods thanks to a hot spare and auto rebuild.

Open-E cover off the reason's why... worth a read.

http://blog.open-e.com/why-a-hot-spa...is-a-bad-idea/

Single 8 disks will give you more flexible way to deal with space, and disks, while using 2 of 4 disks will let you maybe more organized with your data, as if you want to add extra space to a the NAS or iSCSI users you have.

The easiest way now a day to save a backup for all the system is to have an external HDD and save a backup on it, that way you will be in double safe.

Thanks a lot for your input!
I now decided to start with two sets of 4 disks each.

The most interesting point for me is:
What do you think, how the speed will change?
Especially the IO-speed of the iSCSI volume, which should host some VMs for ESX in the future.