[OpenIndiana-discuss] Migrating root zpool from old disks to new one. only one system available

[Jim Klimov]

2012-06-12 16:45, Gary Gendel wrote:
> On 6/12/12 8:00 AM, Jim Klimov wrote:
>>
>> Did the 3TB disk also report to the OS that it uses 4k sectors?
>> What ashift value is used by the pool, ultimately? Example:
>> # zdb -l /dev/rdsk/c2t0d0s0 | grep ashift
>>         ashift: 9
>>         ashift: 9
>>         ashift: 9
>>         ashift: 9
>>
>> If your 4KB disks use ashift=9 it is possible to get problems
>> worse than decreased performance ;)
>
> I'm a bit confused.  I checked my mirrored Seagate ST33000651AS 3TB
> drives using this method and I see "ashift: 9".  I'm sure that the
> Seagates told them it had 512 sectors, but I thought that you couldn't
> see the whole 3TBs with 512 sectors.  I have these striped with a 1TB
> mirrored drive in the pool and zpool list shows 3.62T which seems about
> right.  Is my understanding flawed?

I failed to find the specs on the Seagate site which would state
that this model uses 512B or 4KB sectors, or the Advanced Format.
I thought that only Hitachi Desk/Ultra-Stars had 3TB disks with
512B native sectors (and 4TB models are Advanced-Formatted too),
but that is not definitive. Maybe Seagate did that, maybe not.

As for "ability to see", that's related to the disk size and
the partitioning table used (GPT vs. older MBR, which can only
address 2TB max), and not to the native sector size.

As for the striped pool size - it seems about right.
My 3TB disk is 2.72T, so a 4TB set being 3.6T seems okay.
The raid10 mix also can have mixed ashifts, i.e. using ashift=12
for the 3TB disks and ashift=9 for 1TB disks, if that's configured.

Is your 1TB disk mirrored? Otherwise its single failure can bring
the whole pool down.

HTH,
//Jim