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Can you have a single volume larger than 2TB?

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December 14, 2009 12:14:34 PM

I've been seeing discussions about RAIDs and the 2TB limit on the partitions. Could it possibly mean a 2TB VOLUME limit? I have two machines with two different controllers, both with a 2.7TB RAID 5 set (4x 1TB config). Unfortunately in one array, one drive dropped out and when it rebuilt, I had one single volume instead of two volumes (2TB and 750GB). From what I've seen, that should not be a problem, if I understand it right. However on both machines I can not access that last .7 of a TB. Its listed as unallocated, and all options are grayed out. On machine A, I was using the RAID5 as a boot drive with Win7. On machine B, the RAID5 is a secondary drive. I thought perhaps the MBR was limiting it on machine A. I don't know how to install Win7 using GPT and it will only let me create a 2TB partition, can not create a second 750GB partition either, as I mentioned earlier. Is this an MBR or NTFS limitation?

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a b G Storage
December 14, 2009 1:04:03 PM

The 2 TB limit exists in a few different ways. The first, and hardest to deal with is the limit imposed by older RAID controllers. Since you are seeing a 2.7 TB volume my guess that you are not limited by that. The second 2 TB is a limit imposed by MBR. The workaround for this is creating multible 2TB partitions on the drive. Windows currently limits NTFS to 256 TB so we wont be hitting that at home for a couple months, heh. Have you tried converting your disk to dynamic or something like that in the disk manager. This might allow you to partition the remaining 750 GB. On the system that does not boot off the raid 5, why not just make the 2.7 TB volume a GPT volume and have one partition?
As far as I know you cannot install windows on a GPT so you are out of luck with the boot RAID 5 and any wishes to have 2.7TB of continuous space. If you are using Matrix raid why not just create two volumes? One for boot and one for storage. Lets say a RAID 10 of 200 GB for boot and then the rest RAID 5. This will present two drives to windows 7 during an install and it will let you use the rest of your RAID as a single GPT volume of around 2.3 TB. Another thing to think about is losing data on a boot partition. If you have your OS and data all on the same partition, what happens if windows becomes corrupt and you have 2 TB of data sitting on the same partition to deal with. I like to create a small parition for my Windows install, lets say 150 GB for windows 7. Then I use the rest of whatever drive I have left to store my data. That way, if I do need to complete a full rebuild, I have all my personal data outside of the boot disk. This way you can just wipe the boot drive clean and start from scratch with no worries.
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December 14, 2009 1:25:08 PM

On machine B, I am running Vista, so GPT isn't an option, secondly, I have data in that 750GB partition that I can't get to anymore since the RAID malfunction. I think I can pull it with data recovery software though. I used to have 2 volumes set up, but when it recovered itself I had one 2.7TB volume, and with in that, the old 2TB partition showed up, with an inaccessible 750GB partition.
On machine A, I was doing exactly what you suggested. I had a 75GB boot partition, and a 1.9TB data partition for my dvd & divx files. I would have used the rest of the 750GB if I could, making it around 2.5TB. I don't think the controller is that sofisticated (bad spelling..sorry) that I can do that. I am using a Gigabyte GA-E7AUM-DS2H. It uses GeForce 9400 chipset which I believe also includes the MCP. On machine B, I am using Areca 1210 controller. I had two volumes on that like I said, but when it recovered itself after one of the drives mysteriously dropping off the array, it became one single 2.7TB volume. On machine A, I am thinking about reducing the array by one drive, therefore creating a 1.8TB RAID 5 volume and a 1TB simple volume to use as a boot drive and misc. file storage. Trying to figure this all out has made my head spin! :( 
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a b G Storage
December 14, 2009 3:53:48 PM

Hmm, I thought Vista supported GPT. I skipped that OS so I have no experience with it. Definately recover the data because doing anything with that space might risk even more data loss.
It sounds like you have had some really bad luck, and you are even using some better hardware. I have never heard of recoverys messing with RAID volumes like that. You have me a little scared now. Its a pity to knock one of those 1 TB drives off your areca card just to get things working. Good luck.
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December 14, 2009 4:52:05 PM

Yeah, I don't know what happened there with the Acera. I'm sure its some sort of human error on my part when I did the recovery. I had something happen once before on it and it worked just fine afterwards. Just add the errant drive back as a hot spare and it worked fine. Something else happened this time though...it seems like 3 drives dropped off. My wireing is a little cramped down in my case so I don't know if something came loose. I replaced all the wires now with clip-on type so hopefully nothing like this happens again. The data isn't vital, old school projects, not sure what else.. except maybe my music, which i have a backup, though a few days old..on my network drive, so...
As far as the other machine, the Gigabyte board, I am taking the single drive off to use as a boot drive. It doesn't seem to have the option to create multiple volumes on the Raid set like the Areca can. The Areca cost 3x as much as the whole mobo..so I guess you get what you pay for. I didn't plan on putting a RAID in there in the first place, other than 2x 1TB in RAID0, then thought about backing it up so then I put two more 1TB in there..Was planing on doing RAID0 then using imaging software to back up to the second set of drives. Board didn't seem to be able to do a second raid set then saw that the board supports RAID0+1 which is what I was trying to do in some adhoc way. I also found it did RAID5 which seemed to be a better utilization of space per drive.

goobaah said:
Hmm, I thought Vista supported GPT. I skipped that OS so I have no experience with it. Definately recover the data because doing anything with that space might risk even more data loss.
It sounds like you have had some really bad luck, and you are even using some better hardware. I have never heard of recoverys messing with RAID volumes like that. You have me a little scared now. Its a pity to knock one of those 1 TB drives off your areca card just to get things working. Good luck.

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December 14, 2009 10:16:25 PM

You are correct. Vista does support GPT as well. Learn something new everyday
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