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Former MBR RAID 0 volume is missing ~5% capacity?

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March 26, 2009 2:49:17 AM

If I didn't have 2 identical Raid 0 arrays, then I probably wouldn't have caught this.
"Disk 1" below used to be formatted MBR.
I am trying to re-format it in GPT to regain the missing capacity over the 2TB limit.
See picture:


-Both "Disk 1" and "Disk3" are made up of 3 identical Seagate 750GB Disks
-The Raid manager beside shows the actual capacity of the disks = 698.93GB

-"Disk 3" is correct by my calculations, but "Disk 1" is missing ~105GB or 5%!

The math:

(Disk 3)2048.00 + 49.91 = 2095.91

(Disk 1)1990.97 = 3X698.63 =2095.89 - ~105GB difference!

Because I cannot see the missing capacity, does it perhaps lie in a lower level format than Windows?
How do I regain it?
March 26, 2009 9:01:29 PM

You may have enabled capacity truncation in the RAID configuration. This means the RAID controller will 'truncate' the capacity used to round numbers. In plain english: if your drive is 750GB = 698,5GiB the controller will use only 690GB for example, because it is rounding to round numbers (10GB or 1GB chunks).

But this does not explain your two arrays differ in since so much. Could you show me a screenshot of your RAID configuration? I'm seeing something on the left, might be a utility you used in Windows. Could you tell me how you created both arrays?
March 27, 2009 4:29:57 AM



Translucency said:
You may have enabled capacity truncation in the RAID configuration. This means the RAID controller will 'truncate' the capacity used to round numbers. In plain english: if your drive is 750GB = 698,5GiB the controller will use only 690GB for example, because it is rounding to round numbers (10GB or 1GB chunks).

But this does not explain your two arrays differ in since so much.


I did not see this feature in the settings, but Yes if this is a contributing factor than there is atleast 2 issues because the capacity loss is so great!

105GB / 3-Hard Drives = 35GB/Drive missing

Translucency said:
Could you show me a screenshot of your RAID configuration? I'm seeing something on the left, might be a utility you used in Windows. Could you tell me how you created both arrays?


joshzstuff said:
-The Raid manager beside shows the actual capacity of the disks = 698.93GB

Although the Raid & Hard Drives are identical, I am using 2 separate RAID Managers:
Silicon Image's SATARAID5 from the 3132 eSATA card bundled with my Venus T5 {external enclosure} (LEFT)
& Intel's Matrix Storage Console from my ICH9 {internal} (RIGHT)
Picture:


Notice I included the individual disk sizes quoted by the controllers, BOTH the SAME capacity ???
Related resources
April 7, 2009 11:04:19 AM

UPDATE:

After formatting the former dynamic MBR volume to GPT the results are what was expected:

A single 2095.78GB volume.


Does anyone know what would cause the extra 105GB to go missing from an Identical array but with a different array manager?

Could it be formatted in a level below what Windows/intel can see?
Note: I created the 3-disk array from Vistas Disk Manager with brand new hard drives.

WHY are "Disk 1" and "Disk 3" not the same size?
April 11, 2009 9:03:19 AM

Windows 32bit can't handle more than 2TB LUN's and Intel Matrix Raid doesn't offer 'carving' like most hardware raid controllers. However, you already know about GPT.

I obviously don't know what you use your PC for, but you obviously do not care about data safety with all Raid 0s. Raid 0 is a sore point with me. Its like watching someone try to cross train tracks with a train coming; eventually, that train will make contact.

I think I know what your problem & solution are: use Seagate's SeTools in DOS and see if those 3 drives are reporting the correct amount. I had this problem trying to replace a 60GB drive in a Dell laptop up to a 120GB Seagate drive. Every time I tried copying the data over, it would change the reported size of the drive and I would have to go in and reset it using SeaTools. I even tried creating a Raid 1 array in another pc and that didn't even work.
!