gpart, to -a 4k or to -b 1M

Warren Block wblock at
Sat Nov 16 00:17:00 UTC 2013

On Fri, 15 Nov 2013, aurfalien wrote:

> Hi,
> Curious, for best practice in ensuring 4K alignment, should one do;
> gpart add ... -b 1M
> or
> gpart add ... -a 4k
> Thank in advance,

They do different things.  '-b 1M' starts the added partition at 1M 
but does not force it to be a multiple of 4K in size.

'-a 4k' forces the added partition to start at the next 4K-aligned 
block, and forces the size to be a multiple of 4K.

I recommend both for the first filesystem partition, and '-a 4k' for 
later ones.

More information about the freebsd-questions mailing list