Re: GPT missing after controller swap (wd to ld)

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Oct 10, 2016 at 11:35:04AM -0400, Louis Guillaume wrote:
> [...]
> twa0: AMCC    9550SX-8LP DISK 3.08CH117795F9744600A1E6
> ld1 at twa0 unit 1
> ld1: 1862 GB, 243151 cyl, 255 head, 63 sec, 512 bytes/sect x 3906228224
> sectors
> [...]
> ld1: GPT GUID: fa939ed5-ec03-4ed1-951e-963aec893757
> ld2: GPT GUID: 3e8e9b55-efc9-4748-959d-2c63e92daa42
> dk0 at ld1: boot0
> dk0: 524288 blocks at 128, type: ffs
> dk1 at ld1: disk0
> dk1: 3906504704 blocks at 524416, type: raidframe

524416 + 3906504704 = 3907029120, which is larger than ld1 (3906228224).

I guess that the twa controller uses a few blocks at the end of the disk
for its own metadata, so the volume accessivble by the OS is smaller than
the hardware.

You can indeed destroy/recreate dk1 and dk3, reformat and copy data.
But you may have file blocks in the area which is now hidden, so 
some data may not be accessible with the twa controller.
It's also possible that the twa controller did write its own data here,
in which case your data are definively lost.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--