How to add unused space to an existing install

Warren Block wblock at
Fri Feb 8 03:46:08 UTC 2013

On Thu, 7 Feb 2013, Teske, Devin wrote:
> On 7 Feb 2013, Paul Schmehl wrote:
>> I've been doing some more research on this problem, and I've discovered
>> that bsdlabel has a 2 to the 32nd limit on disk size.  It appears I have to
>> use gpart instead.  Is that not correct?
> Only if your disk is larger than 2TB (or 2048GB). If you try to partition a >2TB disk with fdisk the most you can hope to access is 2TB (the rest will be forever unused).
> I was noticing that that the total size for all your partitions is about 744.95GB -- far short of the maximum addressable of 2TB. So you *could* gain access to more space with the tricks discussed here, but yes...
> You will be required to use gpart to address more than 2TB of storage on a single discrete disk. gpart creates a GPT layout versus fdisk which creates an MBR layout. GPT uses length identifiers double that of MBR so you should be able to address up to 16 million terabytes on any single discrete disk with gpart. That ought to be enough for a while (the largest storage array known to exist today is in the Petabytes ... thousands of terabytes -- nobody has yet produced a single storage device of contiguous addressable space matching-or-exceeding 1024 petabytes or 1M terabytes; so we have a ways to go before anybody reaches the limit of 2^64).

To be exact: fdisk can only deal with MBR partitioning.  bsdlabel only 
deals with FreeBSD partitions.  Both align partitions to CHS values, 
which don't apply to disks made in the last couple of decades.  This 
means that partitions created by these two tools will almost certainly 
be misaligned when created on an Advanced Format (4K) hard drive or an 

gpart(8) can do GPT *and* MBR *and* bsdlabel and other partition 
schemes.  It does all the things that fdisk and bsdlabel do, and more.

For examples of creating both GPT and MBR/bsdlabel partitioning with 

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