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RAID Drive totals not jiving between Array Utility and Disk Management

Posted on 2006-11-30
Medium Priority
Last Modified: 2013-12-03
I have a 2003 server with 5 36.4 gb drives.  3 are currently a logical drive in the array and 2 are unused space in the array.  I am looking to add the two drives to the array but before I commit them I have been looking at different numbers and cannot reconcile what I see.  
My understanding of RAID 5 - you need a minimum of 3 drives, all drives need to be of equal size, the fault tolerance uses space equaling 1 drive size over the course of the total drives.  So if I had 3 drives then 2 would equal available space 1 would be used by RAID Fault Tolerance.  If I had 5 drives then 4 would equal available space and 1 would be used by RAID Fault Tolerance, etc...

Looking in Disk Management I show:
    Disk 0 - Basic - 101.74 GB Online
    C Drive (C:) 67.82 GB NTFS / Healthy (System)
    33.92 GB Unallocated
Equaling 101.74 gb

Looking in the HP Array Configuration Utility I show:
    1 array controller
    1 Parallel scsi array

Under Physical View I show qty 5 of 36.4 gb parallel scsi drives
Equaling 182 gb

Under Logical View I show:
     Logical Drive 1 (104183 MB RAID 5)
     Unused Space 43410 MB
Equaling 147,593 gb

Logical View Total: 147,593 mb
Physical View Total: 182 gb
Disk Management Total: 101.74 gb
Why is my usable space so much smaller than I expect?

Can anyone explain this for me?

Question by:sganci
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LVL 56

Expert Comment

ID: 18048880
>3 are currently a logical drive in the array...
Can't be or you would see no free space in disk manager.

Looks like someone has already added one disk to the array and expanded it then added the other since the 101GB is what you get from 4 36GB disks. It's the 33GB free you currently see in disk manager. It's a bit smaller than the 104GB that's used by Logical Drive 1 because of the master file table, diags partition etc.

>Unused Space 43410 MB
Are you sure that isn't 33410 MB, that would represent the final drive being added but the logical drive not being expanded.

I hope for your sake you haven't converted to dynamic disk in Windows because there's a bug about data loss if expansion is performed twice but that doesn't apply to basic disks and I don't think it applies to 2003 anyway.
LVL 56

Expert Comment

ID: 18052696
>Under Logical View I show:
     Logical Drive 1 (104183 MB RAID 5)
     Unused Space 43410 MB
Equaling 147,593 gb

Logical Drive 1 (104183 MB RAID 5) =  104183 *4/3 = 138911
Unused Space 43410 MB
total 182320 MB - same as physical space.

The reason the unused space is higher than one physical disk is that it takes into account the fact that after creating a new logical drive or extending the current one then logical drive 1 will be spread accross 5 spindles rather than 4 so it's factored that in even though it probably hasn't physically spread it accross all 5 spindles yet.

Author Comment

ID: 18056670
Okay I think I understand now.

1: Unallocated space & C Drive listed in Disk Manager EQUALS Logical Drive 1 in the Array Configuration Utility.
    -Is there anyway to get the unallocated space expanded into Drive C ?

2: The unused space in the Array Configuration Utility if I select to create a New Logical Drive I should then see additional unallocated space in Disk Manager.  Right?

3: One last thing to verify for me if you would - I originally was looking to remove the 5th drive - but was told that since it was seen by the Array Configurator that the only way would be to basically reformat and start from scratch.
Do you know if there is anyway.  (when I tried to remove the drive the system just complains about a hard drive failure with no options to remove it.

Thanks for all your help

Author Comment

ID: 18094977
in addition to the above - If I cannot merge the existing unused space in the current C drive - can I at least take the 2 drives that do not have a drive letter attached and create 1 D Drive?  I have read that programs like diskpart should not be used on the drive with the OS.  
Do you know of any reasonable third party programs - like patition magic - that will do this function for me?

Thanks again
LVL 56

Accepted Solution

andyalder earned 2000 total points
ID: 18095391
No way to remove the drive without wiping and starting again since it.s in the array now.

You can extend the Logical drive with the ACU but since it is the boot partition you can't extend it with Windows. Diskpart won't work on the boot partition. Please avoid converting to dynamic disks, that won't let you extend it either and can cause data loss on extended arrays.

BootItNG from will resize C: for you, when booting from the bootit floppy choose not to install, then you can use it to extend c: to take up the rest of the space. You're meant to pay for it but the trial copy seems to work OK. Obviously backup first just to be safe.

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