2.4TB disk - MBR and GPT coexist?

[Jan Mikkelsen]

Hi,

Jo Rhett wrote:
>> On Thu, 11 Jan 2007 13:56:43 -0800 Jo Rhett <jrhett at svcolo.com> wrote:
>>> Thanks for the reply.  The problem is that I have a single 6-drive
>>> (550gb/ea) RAID-5 array.  If I split two disks off to make a RAID-1
>>> boot device, I'll lose 1TB of usable storage.
>
> On Jan 11, 2007, at 3:55 PM, Torfinn Ingolfsen wrote:
>> Hmm, why can't you just make your controller create two logical arrays
>> onto the one physical array? Doesnt the controller support this  feature?
>
> Not any one that I've ever seen in commodity disks.  Yes, on big  fiber 
> channel disk cabinets.  No to 6-8 drive raid controllers.

I'd be very surprised if you can't.  You can certainly do it with Areca 
(arcmsr(4)), HP (ciss(4)), IBM ServeRAID (ips(4)), although the details 
vary.

For example, on an Areca 8 port controller, I have 8 disks in a RAID-6 
array, and within that "RAID set", I have three volumes.  The three volumes 
appear to FreeBSD as da0, da1 and da2, respectively.

CLI> rsf info
Num Name             Disks TotalCap  FreeCap DiskChannels       State
===============================================================================
 1  Raid Set # 00        8 2560.0GB    0.0GB 12345678           Rebuilding
===============================================================================
GuiErrMsg<0x00>: Success.

CLI> vsf info
 # Name             Raid# Level   Capacity Ch/Id/Lun  State
===============================================================================
 1 ARC-1220-VOL#00    1   Raid6     81.0GB 00/00/00   Rebuilding(63.8%)
 2 ARC-1220-VOL#01    1   Raid6   1000.0GB 00/01/00   Need Rebuild
 3 ARC-1220-VOL#02    1   Raid6    839.0GB 00/02/00   Need Rebuild
===============================================================================
GuiErrMsg<0x00>: Success.


Regards,

Jan Mikkelsen