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Windows 7: using all of raid5 disk space W7x64Pro

13 Mar 2011   #1
Darfyddi

Windows 7 Ultimate x64
 
 
using all of raid5 disk space W7x64Pro

Hi,

I have 4 HDD which should total 4TB and can not figure out how to use all the space that is available after setting them up in RAID5 form.

I currently have:

100.00MB > System Reserved
2047.90GB > 'C' Drive
746.54GB > Un-allocated

I know that it is not possible to have one C drive of above 2047.90GB but I would like to know how I can partition the 746.54GB as a seperate drive and also why the numbers only add up to about 3TB and not 4TB?

Many thanks for any help.


My System SpecsSystem Spec
.

13 Mar 2011   #2
Golden
Microsoft MVP

Windows 7 Ult. x64
 
 

Hi,

In a RAID5 configuration, one of the 4 disks is used as the parity data disk, leaving a total of 3 disks for the total volume available.

From http://en.wikipedia.org/wiki/Standard_RAID_levels
Quote:
RAID 5 usable size
Parity data uses up the capacity of one drive in the array (this can be seen by comparing it with RAID 4: RAID 5 distributes the parity data across the disks, while RAID 4 centralizes it on one disk, but the amount of parity data is the same). If the drives vary in capacity, the smallest of them sets the limit. Therefore, the usable capacity of a RAID 5 array is , where N is the total number of drives in the array and Smin is the capacity of the smallest drive in the array.
See this link as to how it works:

RaidCalc - Raid Disk Space Utilization Calculator - Raid, RAID, Redundancy, Performance - iBeast Business Solutions

Regards,
Golden
My System SpecsSystem Spec
13 Mar 2011   #3
Darfyddi

Windows 7 Ultimate x64
 
 

Cheers Golden,

I thought that was the case but am now wondering about the odd 277.46GB missing over the amount of the 1tb disk, seems a huge amount of space; though not as much as the 746.54GB that I can actually see and marked as un-allocated but wont let me touch it

[EDIT]

Sorry, just wanted to say thank you for the link to the RaidCalc site, it showed ~211GB would be used so that might be the 277GB I can't account for.
My System SpecsSystem Spec
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13 Mar 2011   #4
Golden
Microsoft MVP

Windows 7 Ult. x64
 
 

Hi,

The "missing" 277GB is actually used in "creating" the RAID - that is normal, although the actual amount varies a little depending on the disks and RAID controller. See image below.

Can you post a maximised image/screen capture of your Disk management so we can see this unallocated 746GB?

Regards,
Golden


Attached Images
 
My System SpecsSystem Spec
14 Mar 2011   #5
kado897

Microsoft Community Contributor Award Recipient

Microsoft Windows 7 Home Premium 64-bit 7601 Multiprocessor Free Service Pack 1
 
 

Quote   Quote: Originally Posted by Golden View Post
Hi,

In a RAID5 configuration, one of the 4 disks is used as the parity data disk, leaving a total of 3 disks for the total volume available.

From Standard RAID levels - Wikipedia, the free encyclopedia
Quote:
RAID 5 usable size
Parity data uses up the capacity of one drive in the array (this can be seen by comparing it with RAID 4: RAID 5 distributes the parity data across the disks, while RAID 4 centralizes it on one disk, but the amount of parity data is the same). If the drives vary in capacity, the smallest of them sets the limit. Therefore, the usable capacity of a RAID 5 array is , where N is the total number of drives in the array and Smin is the capacity of the smallest drive in the array.
See this link as to how it works:

RaidCalc - Raid Disk Space Utilization Calculator - Raid, RAID, Redundancy, Performance - iBeast Business Solutions

Regards,
Golden
Just to be clear. It doesn't use a single physical disk for parity. It stripes the data and parity across all four disks so that if one physical disk fails you lose no data.
My System SpecsSystem Spec
14 Mar 2011   #6
Golden
Microsoft MVP

Windows 7 Ult. x64
 
 

Quote   Quote: Originally Posted by kado897 View Post
Just to be clear. It doesn't use a single physical disk for parity. It stripes the data and parity across all four disks so that if one physical disk fails you lose no data.
Thanks for clearing that up Kado
My System SpecsSystem Spec
14 Mar 2011   #7
kado897

Microsoft Community Contributor Award Recipient

Microsoft Windows 7 Home Premium 64-bit 7601 Multiprocessor Free Service Pack 1
 
 

You are welcome.
My System SpecsSystem Spec
14 Mar 2011   #8
Darfyddi

Windows 7 Ultimate x64
 
 

Thank you as well Kodo, that info' along with that about the raid itself taking up space helps alot.

Here is a pic, sorry about it's size. As you can see, I have right clicked on the un-allocated area to show the lack of options available.

My System SpecsSystem Spec
15 Mar 2011   #9
Jonathan_King

Windows 7 Professional x64
 
 

Hello Darfy,

Try using Partition Wizard to create a new volume in that space. We'll see if a different program can get the job done.
My System SpecsSystem Spec
15 Mar 2011   #10
Darfyddi

Windows 7 Ultimate x64
 
 

Cheers, I will try it in a little later or tomorrow and will let you know how it goes
My System SpecsSystem Spec
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 using all of raid5 disk space W7x64Pro




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