gmirror question

[Ivan Voras]

Martin Badie wrote:
> Hi,
> 
> I have a gmirror system (FreeBSD 6.3). Normally on seagate.com I can see that both disk (ST3250310AS  and ST3250318AS) have same layout and the sizes are equal. I have built gmirror using http://people.freebsd.org/~rse/mirror/ what I want to ask is that ad6 was broken and i have replaced it with the new one (new ad6) both on the fdisk command output  i see different sizes (ad6 is bigger than ad4). What i want to ask is that if i rebuild mirror using following command does that break OS ?
> 
> # sysctl kern.geom.debugflags=16
> # gmirror forget gm0
> # dd if=/dev/zero of=/dev/ad6 bs=1k count=1
> # fdisk -BI ad6
> # bsdlabel -B -w ad6s1 auto 
> # gmirror insert gm0 /dev/ad6s1
> # gmirror status
> 
> 
> 
> The disk details are like:
> 
>  grep ad4 /var/run/dmesg.boot 
> 
> ad4: 238475MB <Seagate ST3250310AS 3.AAF> at ata2-master SATA150
> GEOM_MIRROR: Device gm0: provider ad4s1 detected.
> GEOM_MIRROR: Device gm0: provider ad4s1 activated

In other words, you are mirroring the first partition/slice from ad4 to 
the first partition of ad6? Apart from this being strange and sometimes 
useless, it will work as long as the sizes match.

(the "new" drive/partition size can be larger than the old, but cannot 
be smaller)