10.1 geom "diskid"

[Freddie Cash]

On Wed, Nov 19, 2014 at 8:08 AM, Alan Somers <asomers at freebsd.org> wrote:

> On Wed, Nov 19, 2014 at 8:55 AM, Patrick M. Hausen <hausen at punkt.de>
> wrote:
> > Now it's getting decidedly weird:
> >
> >> Am 19.11.2014 um 16:40 schrieb Patrick M. Hausen <hausen at punkt.de>:
> >>
> >> Hi, all,
> >>
> >> next question, sorry. I just created a fresh 10.1 installation
> >> with ZFS. With the last reboot after adding dedicated SSD
> >> based l2arc and zil, the underlying devices are referred to
> >> by "diskid" instead of the GPT labels I have first been using:
> >>
> >>       NAME                                STATE     READ WRITE CKSUM
> >>       zroot                               ONLINE       0     0     0
> >>         mirror-0                          ONLINE       0     0     0
> >>           gpt/disk0                       ONLINE       0     0     0
> >>           gpt/disk1                       ONLINE       0     0     0
> >>       logs
> >>         diskid/DISK-BTTV334403R7200GGNp2  ONLINE       0     0     0
> >>       cache
> >>         diskid/DISK-BTTV334403R7200GGNp1  ONLINE       0     0     0
> >>
> >> I can live with that, but I do not understand why the ada2 device
> >> changed from gpt/* to diskid/* while the others did not?
> >>
> >> /dev/gpt entries are not even present for ada2, neither are ada2p?
> >>
> >> At least the system could try to be consistent ;-)
> >
> > gnop create -S 4096 /dev/diskid/DISK-BTTV334403R7200GGNp3
> > zpool create ssd /dev/diskid/DISK-BTTV334403R7200GGNp3.nop
> > zpool export ssd
> > gnop destroy /dev/diskid/DISK-BTTV334403R7200GGNp3.nop
> > zpool import ssd
> > zpool status
>
>
> Why the gnop acrobatics?


​Future-proofing the pool.  :)  It's going to get harder and harder to buy
512B harddrives, meaning that at some point, the drives will be replaced
with 4K drives, and performance will (potentially) tank on the pool​.  If
you build the pool from the get-go with an ashift of 12 (4K sectors), then
you won't have any issues in the future.

-- 
Freddie Cash
fjwcash at gmail.com