FreeBSD 9 and gmirror /geom raid

[Davide D'Amico]

In data 08 marzo 2012 alle ore 17:27:30, Freddie Cash <fjwcash at gmail.com>  
ha scritto:

> On Wed, Mar 7, 2012 at 8:58 PM, Davide D'Amico
> <davide.damico at contactlab.com> wrote:
>> Il 08/03/12 00:02, Freddie Cash ha scritto:
>>>
>>> On Wed, Mar 7, 2012 at 6:14 AM, Davide D'Amico
>>> <davide.damico at contactlab.com>  wrote:
>>>>
>>>> Hi, I have a server DELL R210 with two sata drives:
>>>> ada0 at ahcich0 bus 0 scbus0 target 0 lun 0
>>>> ada0:<SAMSUNG HE253GJ 1AJ30001>  ATA-8 SATA 2.x device
>>>> ada0: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
>>>> ada0: Command Queueing enabled
>>>> ada0: 238418MB (488281250 512 byte sectors: 16H 63S/T 16383C)
>>>> ada0: Previously was known as ad4
>>>> ada1 at ahcich1 bus 0 scbus1 target 0 lun 0
>>>> ada1:<SAMSUNG HE253GJ 1AJ30001>  ATA-8 SATA 2.x device
>>>> ada1: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
>>>> ada1: Command Queueing enabled
>>>> ada1: 238418MB (488281250 512 byte sectors: 16H 63S/T 16383C)
>>>> ada1: Previously was known as ad6
>>>>
>>>> Previously (8.x) - when I didn't use a hw raid - I used to install
>>>> freebsd
>>>> in a drive (i.e. ad4), boot from it and then:
>>>>
>>>> # sysctl kern.geom.debugflags=16
>>>> # gmirror label -v -b round-robin data ad4
>>>> # gmirror insert data ad6
>>>> // Modification to /etc/fstab
>>>> // reboot
>>>>
>>>> How could accomplish to the same task with 9.0-RELEASE?
>>>
>>> http://people.freebsd.org/~rse/mirror/
>>>
>> Hi Freddie, and thanks for your link.
>>
>> I followed that procedure until 9.0-RELEASE but the new installer uses  
>> GPT
>> as the default partition schema, which seems incompatible with gmirror.
>>
>> I noticed in the handbook
>> (http://www.freebsd.org/doc/handbook/geom-mirror.html):
>> "The following procedure is also incompatible with the default  
>> installation
>> settings of FreeBSD 9./X/which use the newGPTpartition scheme. GEOM will
>> overwriteGPTmetadata, causing data loss and possibly an unbootable  
>> system."
>>
>> So I think that the old procedure is no more useful.
>
> There's nothing preventing you from using MBR partitioning with BSD
> labels, just like in previous releases.  Especially since you only
> have 250 GB harddrives (GPT is only required for disks over 2 TB).
>
> If your primary goal is to have mirrored disks, then your best setup
> is to gmirror the disks, MBR partition the gm0 device, then BSD label
> the slices.
>
> There's nothing carved in stone anywhere that requires you to take the
> defaults as gospel.  :)

Ok, thanks.

d.