Re: RAIDframe and alignment on 4K-sector disks?

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

On Sun, 18 Jun 2017, Greg Troxel wrote:

> "John D. Baker" <jdbaker%mylinuxisp.com@localhost> writes:
> 
> > It turns out the 2TB disks for the planned RAID-5 also have 512-byte
> > native sectors, not 4K sectors.  So no alignment constraints after all.
> 
> Until one fails and the replacement is 4K.

True.

> But, I think this is just a matter of using 64 instead of 63 for the
> partition start. and then things are lined up adequately.

Or not even that.  As long as offset and size are a multiple of 8 (or
8 * num_data_disks for a RAID), it will be good enough.

I'll proceed as if the disks were 4K anyway.

(My habit is to start 512n PeeCee bootable disks at sector 1 and thereafter
align to the disklabel-reported cylinder size).  If its likely I'll end
up replacing one with a 4K disk, I'll start at sector 8 and round up
the sizes accordingly.  Data-only disks get the default disklabel starting
at sector 0.)

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