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Partitions of size > 2TB: How do we implement GPT, GUID, EFI and gdisk?

Posted by davygravy 
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davygravy
Partitions of size > 2TB: How do we implement GPT, GUID, EFI and gdisk?
May 15, 2012 05:57PM
The question is not philosophical, but rather practical. We'll be moving to larger hdd's soon. For the entire Kirkwood community... ALARM folks please chime in to as we all use Linux and U-Boot..

What do we need, from the ground up? What is missing from this list?
  • a kernel that has support for EFI & GPT
  • gdisk utilities in A) our Wheezy Debootstrap script B) in any future Rescue System (in NAND)
  • U-Boot that recognizes GUID/GPT/EFI
  • changes to e2fsprogs (? : I'm not aware of any changes that need to be made for this, but just want to make sure...)
  • ?? what else




Stuff to consider:
http://www.rodsbooks.com/gdisk/hybrid.html
http://www.rodsbooks.com/gdisk/index.html
http://forum.doozan.com/read.php?2,6309,6313#msg-6313

...more?... better?...

Or is this something that is not a priority here. Is it something that a trivial workaround can solve transparently and seamlessly?

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Edited 2 time(s). Last edit at 05/15/2012 06:08PM by davygravy.
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WarheadsSE
Re: Partitions of size > 2TB: How do we implement GPT, GUID, EFI and gdisk?
May 16, 2012 10:57AM
The easiest method is GPT+Hybrid. Enabling GPT disk access is quite easy, and is supported by the ALARM kernel out of the box.

u-boot can read the hybrid to get to the boot partition, and then the kernel reads the GPT. The obvious flaw in this is the ordering of the partitions could be flawed by a user so that the boot/rootfs partition are in opposing orders (I won't go into detail, read up on hybrids) but so long as the are appropriately matched, you should be ok.

One possible option:
GPT: rootfs, boot, data
Hybrid MBR: boot, hidden

Thus to u-boot the boot partition shows as the first partition, and to the kernel, rootfs shows as the first partition, happily making /dev/sda1 accurate (or whatever parlance wished)
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davygravy
Re: Partitions of size > 2TB: How do we implement GPT, GUID, EFI and gdisk?
May 26, 2012 12:04AM
handy reference...
http://www.rodsbooks.com/gdisk/walkthrough.html

gdisk on the RescueV2.8 is now tested at least a little bit and works... I unfortunately don't have a 3TB drive to check it out on (in terms of > 2TB)...

and the final uboots work w/ EFI...

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Edited 1 time(s). Last edit at 05/26/2012 04:58PM by davygravy.
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