HP StoreVirtual 4530 4TB available disk space

[CB221]

Hi all

Looking to purchase the HP StoreVirtual 4530 4TB MDL SAS Storage(F3J69A) x 2 Nodes.
It has 4TB 6G 7.2K x 12 disks.

I need at least 24TB of available storage in a resilient 2 node cluster, i.e if one node goes down then everything keeps running.


Please can you let me know if 2 nodes are configured in a RAID10 cluster (I understand RAID 5 is possible only with 3 nodes) what the available storage will be?

Thanks

P.S. This thread has been moved from torage Area Networks (SAN) (Small and Medium Business) to HP StoreVirtual Storage / LeftHand. - Hp Forum Moderator

[oikjn]

I"m not sure about that specific node, but typically the HARDWARE raid is done with two groupds of raid5, but I think there are some that are now raid6 and I wouldn't be suprised to see this is one of them,

On top of that, your LUNs should be protected at NETWORK Raid 10 which pretty much means for a two node cluster, you can take the usable space of one node and that is your usable space in the SAN.  From then on, any additional node you add to the cluster will give you 1/2 of its actual capacity as usable space to the SAN.  

Yes this is VERY wasteful when it comes to usable space vs. Raw space, but that is the price you pay for the redundancy you get here... and that is hard to beat.

[CB221]

OK thanks.

So from your reply I take it that 22TB would be available in a two node cluster with 4TB x 12 drives in each node.

This is based on the configuration as follows

NODE 1 - StoreVirtual 4530 - RAID 5 (Hardware) local 4TB x 12 - 4TB = 44TB useable space (RAID5)
NODE 2 - StoreVirtual 4530 - RAID 5 (Hardware) local 4TB x 12 - 4TB = 44TB useable space (RAID5)

Create a RAID 10 x 2 NODE Cluster (network using the CMC) 44TB / 2 = 22TB useable space in the cluster.

Can you confirm?

[oikjn]

close...  I think it splits it into two raid5 groups which would mean you get 2x 18.7TB per raid5 group... 37.4TB per node of formatted space (since 4TB drives don't actually give you 4TB formatted capacity).

Then each node would have 37.4TB usable not 44TB which would mean your cluster would have 74.8TB of usable space, BUT the network raid level is actually specified at the LUN level, NOT at the cluster level.  That is more or less academic as you should assume ALL LUNs should be NR10, so you should plan that your actual available space for you to use is 37.4TB.

Might sound complicated, but it really isn't once you get used to it.  The thing that trips most people up when figuring out actual usable space is that you first have to apply the hardware raid calculations and then you have to apply the network raid on top of that.  Unfortunately the actual net usable space is always crap compared to the available space, but that is just a nature of the beats to provide you with the ultimate redundancy and availability this SAN can provide.

Personally, on my VSAs, I'm often running Raid10 and then NR10 on top of that!  that gives me a 1:4 ratio of usable to raw storage capacity, but in my case I only need ~6TB usable, so I'm fine with the inefficiencies.  If I needed 600TB, that would be a whole other story :)

[CB221 · Accepted solution]

Great, sounds good.

Around 37.4TB of available space it is then!

Thanks for your time on this.

[pvdveen]

The P4530 4 tb is confiured with a raid 6 disk set. So you lose 2 of the 12 disks.

It can official not be configured as a raid 5.

See my problems with a P4530 3 Tb.

http://h30499.www3.hp.com/t5/HP-StoreVirtual-Storage-LeftHand/P4530-36-TB-usable-space-only-22-TB/td-p/6470830#.U_UDO7x_uzk

[oikjn]

two raid 5 groups or one raid 6 group pretty much gives you the same net storage space, so the net usable size for the node should not change.  I understand using raid6 for such large drives...  when a rebuild is needed, the time it would take while being unprotected is just too long for comfort with single parity.

[CalvinZito]

@CB221,

Did you get your questions answers on HP StoreVirtual?  I'm happy to help get any further questions you have answered.  Just reach out to me either here or with a PM. 

Calvin