P4530 36 TB usable space only 22 TB

[pvdveen]

I have sold 4 P4530 36 TB MDL model B7E24A to a client. With a exspected usable space of about 60 TB.

The problem is that the usable space of per p4530 is only 22 TB!

The unit has 12 3TB mdl disk configure in 2 raid 6 disk sets. So I loose 4 of the 12 disk.

It is not possible with the P4530 3TB an the 4TB mdl model to configure the raid set as a raid 5 like all other models. In the specifications of the p4000 serie there is a very very very little "warning" about it. And in the specs of the P4530 36 TB there said disk raid 6. But notthing about the consequent of loosing so much usable space.

Does any one have a idea to get the 60 TB of storage. I can give up the multisite configuration.

I already tried the networkraid 5 configuration. But that doesn't give me more space.

I really don' understand why HP disabled the raid 5 option.

And is there a good space calculator for the P4000 serie with the different network raid options?

[oikjn]

they probably dissabled it because the rebuild time of a 3TB drive group that large is just too long to be acceptible for raid5.  Talk to whomever you purcahsed the units from.  This is a sales question/problem.  The SAN requires what it requires on the physical drive storage and it requires NR10 for any production data (NR5 is only for archive retrieval data).  If you purchased the units because you thought you were going to get more space, then you should return them as there is no way to get more space short of adding another node.

If you need 60TB of usable storage you need to purchase another node or return them all and look into the VSA software option.  

unless you have a really high availability/protection requirement, the StoreVirtual system might not be the ideal choise for you since you have to purchase 2x your storage requirements for network raid and that is on top of the losses from hardware raid.

[pvdveen]

oikjn

Thanks for your reply.

We are selling these systems and this was the first time we sold the p4530 3TB version (and the last time). I think i have to return the untis back to HP :-).

[oikjn]

yea I think so.  They really should list the nodes by size according to actual default formatted capacity and not raw drives, but I guess we can expect that when hard drive manufacturers follow that logic as well.

[pvdveen]

After a few support calls with HP about my space problem. They admit that the chosen raid construction is not very efficient. But they cannot tell why lefthand have chosen this configuration.

The 2 TB and 4 TB version have a much more efficient configuration.

I ask if it would be possible to make the 4 TB configuration. This is 12 drives in one raid 6 set. So I only lose 2 drives. But this is  not supported. Why not the cannot explain.

example of the different p4530 configurations.

4530 2 TB: 2 raid set with 6 drives in raid 5 = total usable space 2 x 5 x 2 TB = 20 TB (offer 2 drives)

4530 3 TB: 2 raid set with 6 drives in raid 6 = total usable space 2 x 4 x 3 TB = 24 TB (offer 4 drives!!)

4530 4 TB: 1 raid set with 12 drives in raid 6 = total usable space 10 x 4 TB = 40 TB (offer 2 drives)

In the specification is only mentioned that the 4530 3TB and 4 TB have only hardware raid 6 and 10. But there is noting in the specifications that the 3 TB version lose 4 drives and the 4 TB only lose 2 drives.

I found in the release notes of saniq 11 that the p4530 4 TB is configured as one raid 6 set. Noting about the 3TB version. 

I can understand that lefthand choice for raid 6 because of the very long rebuild time when a drive is replaced. And this I can sell to my customer. But not 4 drives of 12.

will be continued

[oikjn]

yea sounds like you have to find the right contact at HP...  btw HP=lefthand for a few years now :)  I would think IF they offer a 12 drive raid6 option for 4TB SOMEONE there should be able to enable that for 3TB drives, but maybe they don't offer it for 4TB drives eitehr and its just a documentation glitch.  Either way, I can understand how your customer would be upset that 36TB turns into 24TB and suddenly their 144TB of raw storage ends up as 44TB of usable SAN space!  EEK!  The StoreVirtual System does enough to kill usable space w/ NR10.

BTW, w/ two raid6 groups, you could almost go to raid10 and end up with 18TB of space.

One silly idea...  is this a single site and is that 60TB really what you need?  Reason I ask is that you get exactly 60TB with FIVE nodes with 24TB each and then you don't have the opimal number of managers running without a FOM.  You also get increased performance for the cluster as well.  Maybe you can make enough noise to either get a 5th unit or at least a heavy discount on one, bu this isn't an option if you need this to be multi-site.  

[pvdveen]

Oikjn,

I sold the lefthand, sorry HP store virtual solution, in a multisite configuration. Client want his data stored on 2 locations. 

We are talking to HP for a good solution. We sold the last month already 3 solutions to different clients. So they now that we are serious (i hope). Support also admits that the configuration of the 3 TB version is not good. But they are not supporting a different raid settings than raid 6 with 6 drives and raid 0. Why not the still cannot tell. Maybe for compatibility with the already sold unit. 

Will be continued

[tkaufman]

Has anyone found out if it is possible to reconfigure the P4530 3 TB units to have just 1 RAID 6 array instead of the 2 so that we don't lose so much space?

We were shocked to learn that the 3TB units were configured this way and it makes no sense why the 3TB version has to have 2 RAID 6 arrays and the 4TB version can work with just 1 big RAID 6 array.

Any further insights by anyone would be greatly appreciated.

Thanks.