EVA 4400 moving disk to another group?

[grem1in]

Hi.

I have 2 disk groups: 8 x 146Gb and 8 x 300Gb.

First group configured as two RAID1 partitions and then striped software RAID0 by Windows 2008 R2 on blade server.

2nd disk group configured as two RAID5  partitions and connected to another blade server.

I need to extend space on 1st blade server. Can I ungroup one disk from 2nd disk group and attach (group) it to 1st disk group without data loss? How to make this procedure more smoothly without data loss and stopping services?

Has anyone experience like that?

[Johan Guldmyr]

Hi, 8 is the minimum amount of disks you can have in a disk group.

So you cannot ungroup it. It's possible to have less than 8 'abnormally' so because of disk failures etc.

I suppose you could just plug it out but sounds like a risky move.

Also will that work? What will happen when you put the disk that was pulled out (marked as bad?) back in?

As it's VRAID1 in DG1 you'll lose half of the 300GB disk.

http://h30499.www3.hp.com/t5/Storage-Area-Networks-SAN/Minimun-number-of-disk-in-a-diskgroup-Eva-8400/td-p/4740240

The higher occupancy you have, the slower the ungroup process is (it's for example also impacted negatively by highly loaded system).

[grem1in]

Thank you. I forgot about "magic" number 8.

It's very bad I can't change RAID level "on the fly".

[Greybeard]

It would also be a very bad move to mix 146 and 300 GB disks in a single disk group. When using a disk of double the capacity it gets twice the number of writes so as to use the same percentage of the disk, therefore if the 300 fails you could be in trouble with the vraid 1. Also it would make it totally impractical to use any protection level since the reservation is based on the capacity of the largest disk, so protection level of single with 146 = reserved space of roughly 300 but if you asdd a single 300 then reserved space would jump to 600 for a net loss of available capacity.