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HP P2000 G3 Vdisk expansion

Hi Experts,

Wanted to ask a question on a HP P2000 G3 which I need to expand the current Vdisk and expand the volume.

The situation: Current P2000 G3 has one Vdisk RAID 5 with 14 2TB disks though this is rapidly running low. 7 x 2TB new disks have been purchased to increase the capacity of the MSA.

Looking on the expand Vdisk section of the Vdisk I can see that there are only 2 slots available left to expand the Vdisk though that will leave me with 10TB of unused available capacity. It seems as though a Vdisk can only contain a certain number of disks (16)

I'm thinking I will have to create another Vdisk and configure the remaining disks as another volume?

I've never configured storage so a little bit apprehensive.
HP-MSA-P2000.png
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damejen
Asked:
damejen
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1 Solution
 
andyalderSaggar makers bottom knockerCommented:
Max disks in a RAID 5 Vdisk is indeed 16 which is far too many anyway, you should never have more than 6 or 7 disks in RAID 5 since the chance of a double disk failure gets too high. read this - http://www.zdnet.com/blog/storage/why-raid-5-stops-working-in-2009/162

There's no RAID level migration available for P2000 unfortunately, I guess you'll just have to pray you don't get an unrecoverable read error if a disk fails, it's not quite as bad as the maths in the zdnet article makes out, UREs are fewer on enterprise disks, even the slow nearline ones.

As to the 7 new ones I'd make a RAID 6 or RAID 10 Vdisk on them unless you really want lots of disks in the Vdisk in which case RAID 50 allows 32 disks per Vdisk.
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damejenAuthor Commented:
I've created a new vdisk and volume with RAID 6. Though I can see it on the Storage Management Utility I cant see the new volume on the Server.

I've re-scanned, refreshed on Disk Management on the Server Manager, what am I missing to allow the server to see the new volume?
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andyalderSaggar makers bottom knockerCommented:
You have to configure volume mapping so the new volume is presented to the host. I think it's under Provisioning > Manage Host Mappings.
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damejenAuthor Commented:
Ok I  managed to find it though I think I may have gone wrong somewhere along the line.
I tried to map the volume on both Hosts, and Im not sure but I think that caused my original volume on the server to seem as though it had been formatted.

I unmapped the newly created volume on both hosts in Storage Management Utility and bounced the server. Original volume re-appeared as normal

Was/am I only to map it on one of the hosts?
MSA-Hosts.png
Second-Volume-on-First-host.png
Second-volume-on-second-host.png
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andyalderSaggar makers bottom knockerCommented:
If your hosts are running clustering software and are clustered together it should be OK to map both hosts to the same volume, if they aren't then it will corrupt very quickly unless they are running a shared filesystem; for example NTFS keeps the master file table in RAM so if one server writes to disk then the other will not know about it since its copy of the MFT hasn't been updated.

So yes, you're only meant to map it to one host in general.
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damejenAuthor Commented:
No clustering is not configured, its a single host connected to 2 enclosures, the thing that makes me nervous is that the first volume uses the entire 1st enclosure and 2 bays in the 2nd enclosure.

If I am to map the new volume to the 2nd enclosure would that affect the 1st volume two disks are in the 2nd enclosure.

Thanks.
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andyalderSaggar makers bottom knockerCommented:
It doesn't matter which enclosure the disks are in so long as they're in the correct Vdisk and the Vdisk is just presented to a single host. The host doesn't connect to both enclosures, it connects to the controllers in the main enclosure and the controllers then connect to any additional disk enclosures.

It's a good idea to spread disks across enclosures if possible, say you had 4 enclosures and a 4 disk RAID 5 Vdisk. If you put one disk in each enclosure you could not only survive a disk failure but also a total enclosure failure so long as it wasn't the main enclosure which the servers connect to that fails.
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damejenAuthor Commented:
I've presented the new volume to the OS as described above. I also created a new LUN as it gives you the option to do so when mapping the volume to the enclosure.

Thanks for all the help andyalder.
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