Split one virtual disk into two virtual disks PERC H710

Question

Hello guys,

- We have a PowerEdge R720 server with a PERC H710 Mini storage controller that has 8 disk of 1 TB each one.

- We created one virtual disk that includes the 8 physical disks configured on Raid 5.

- We installed Windows 2008 Server R2 and we got 4469 GB unallocated space that we cannot use due to the limitation of the basic disks.

What we really want to do is to retrieve the unallocated space from the existing virtual disk and put it into a new one, so that we keep 3 disks for the virtual disk 0 and we use the 5 other for the new virtual disk 1.

- Is that possible without destroying the data we have ?

- Help please !

Thanks in advance and sorry for the bad English :(

theflash1932 · Accepted Answer

Unfortunately, there is no way to do this without starting over.

Option 1

As you described, you could split the disks up into separate VD's, leaving one 2TB or smaller for the OS. This will cost you an extra disk's worth of disk space (VD0 RAID 5 = 2TB, VD1 RAID 5 = 4TB).

Option 2

You could create "slices" across the disks - you would still have all 8 disks in a disk group, but you would carve out a smaller VD for the OS, then the remainder of the disk space could be a VD for data (each VD will show as a separate "disk" in Windows, so the second VD could be converted to GPT and be as large as you want, while the first VD remains an MBR disk for booting the OS in BIOS mode. This will give you back an extra disk's worth of disk space over Option 1 (VD0 RAID 5 = 100GB, VD1 RAID 5 = 6.9TB).

Option 3

You could switch to UEFI mode, create one VD with all 8 disks (as you have done), convert the disk to GPT, then install. UEFI is required to boot GPT disks and GPT is required for disks larger than 2TB. This would also allow you to keep 7TB of usable disk space.

You might also consider a RAID 6, if you can afford yet another 1TB disk's worth of disk space. Given that a disk rebuild could take 1-2 full days or more, a RAID 6 would provide better fault tolerance and protection during the vulnerable time that the disk is offline and/or rebuilding.

Dev Mgr · Answer

One side note to theflash1932's option 2; if you slice a raid set, you will never be able to add any additional drives to the raid set (to grow it). Options 1 and 3 don't have the limitation.

Obviously, if your server has no more drive slots available than that you are already using, this isn't really an issue anyway.

Bueno_contigo · Answer

Thanks a lot theflash1932 for the explanation even if that made me somewhat frustrated coz I have a big amount of data to backup :((

Well, I'll choose the option 3, but could you please explain a little bit more how can I deal with this ? Is there any changes to do in BIOS ?

Many thanks again and sorry for disturbing...

theflash1932 · Answer

Option 3 involves booting to the BIOS and changing the boot mode to UEFI. Then boot to CTRL-R and configure RAID in whatever configuration you choose - don't forget to choose the Advanced and Initialize boxes. When you boot to the OS media, you will need to first choose Repair Your Computer, Command Prompt, then run:

diskpart

select disk 0
convert GPT
exit

exit

Once converted to GPT, you can install the OS.

Bueno_contigo · Answer

Hi theflash1932, OK, understood, I have just one more question please :) Is it possible to make an image of the C: partition (already MBR) and resotre it later on the new GPT partition ? Thanks again !!

theflash1932 · Answer

I can't say for sure, but I don't 'think' this can be done because of the difference in how boot settings are stored on the disk ... there might be a way to do it though.

Bueno_contigo · Answer

Hi theflash1932, Well, that was possible, the file structure is NTFS for both GPT and MBR, here is what I did exactly : 1- Backup the C: partition with CloneZilla (choose expert mode, and ntfsclone method priority) 2- Change boot method to UEFI in the Setup entry 3- Boot with Win2008 DVD (choose Repair)and do the following : 4- Reboot again and do a clean installation of Win2008 5- Reboot with cloneZilla-live and press F11, choose Bios boot and select the DVD-drive. 6- Once under cloneZilla to restore the partition, choose expert mode and DON NOT RESTORE THE MBR ! You may need to look at this 7- After restoring the partition, reboot the server 8- Windows will boot and a checkdisk will be performed, DO NOT SKIP IT This solution is based on this That's all ;)

PowerEdge HDD/SCSI/RAID

Split one virtual disk into two virtual disks PERC H710

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