topic Re: P4500 useable storage in StoreVirtual Storage

P4500 useable storage

mvoss18 — Thu, 13 Jan 2011 02:39:51 GMT

First time with the P4500s, and just looking for a little guidance on the RAID settings. We have a 3-node cluster setup, each with 12x 600GB SAS drives, so 21.6TB total. We're running SanIQ 9.

The nodes come with hardware RAID 5 by default, and I was looking at the network RAID options and most of them eat up a ton of your usable space when you run those on top of the hardware RAID 5.

I spoke with a rep, and he was suggesting doing Network Raid 5 for our environment, but to not couple that with HW RAID 5. Maybe I'm misunderstanding--so should the HW RAID setting be RAID 0 and the Network RAID set to RAID 5? Or visa versa? We would like to be able to survive with the loss of a single node in our 3-node cluster.

Bottom line, what's the "typical" configuration that balances usable storage with data protection? Doesn't make sense to buy 21TB of RAW storage and only get 8TB usable!

Thanks!

Re: P4500 useable storage

Sudhakar Subramaniam — Thu, 13 Jan 2011 09:57:02 GMT

HI,
Yes you are right, the p4000 goes with hardware raid 5 by default..HP recommendation is to have hardware raid 5 and network raid 2, so that they have two non adjacent node level redundancy...they can go for network raid 5 but it is generally not recommended in a performance intensive environment because when we have n/w raid 5 or 6, it takes out some performance in parity writing...but n/w raid 5 gives 1 node failure redundancy and n/w raid 6 gives 2 node failure redundancy. in n/w raid 2,3,4 it doesnt calculate parity and hence a bit faster

Re: P4500 useable storage

Sudhakar Subramaniam — Thu, 13 Jan 2011 09:58:25 GMT

in N/w raid 5 you get 60% of storage space utilization and n/w raid 6 gives you 55%

Re: P4500 useable storage

mvoss18 — Thu, 13 Jan 2011 13:06:32 GMT

I believe the terminology has changed with San/IQ 9. Here are the options we see with a 3 node cluster. I believe NW Raid 6 is available for 4-node clusters.

Network RAID-0 (None)
Network RAID-10 (2â Way Mirror)
Network RAID-10+1 (3â Way Mirror)
Network RAID-10+2 (4â Way Mirror)
Network RAID-5 (Single Parity)

Is Network RAID 2 the same as Network RAID 10 in SAN/IQ 9? With that you would get 8TB usable out of 21.6TB RAW in my environment. Ouch!

I'm under the impression that with San/IQ 9, you can run Network RAID-5 across a 3 node cluster and this will tolerate one of the three nodes going down.

Re: P4500 useable storage

Mark... — Fri, 14 Jan 2011 11:41:21 GMT

Hi
Network RAID-0 (None) = N0, same as before
Network RAID-10 = N2
Network RAID-10+1 = N3
Network RAID-10+2 = N4
Network RAID-5 (Single Parity) new with SAN/iQ V8.5
Network RAID-6 (double Parity) new with SAN/iQ V8.5
Mark...