New g_part class

[Simon L. Nielsen]

On 2007.02.07 22:16:38 +0100, Ivan Voras wrote:
> Poul-Henning Kamp wrote:
> 
> > You mean writing to sectors which mounted filesystems belive they
> > have exclusive use of ?
> > 
> > No, GEOM doesn't support or allow that.
> 
> Ok, the need for sysctl kern.geom.debugflags=16 arises because the live
> system to be used as master has mounted partitions, and those partitions
> span the whole disk, thus conflict with gmirror which wants to use the
> last sector. Since using the last sector for metadata is The Official
> Way, how about making such conflicts easy to avoid, like for example
> building additional logic in g_part to create partitions one sector
> smaller than the container?

Eh, gmirror already does the right thing... :

[root at eddie:simon] gmirror status gmd0
       Name    Status  Components
mirror/gmd0  COMPLETE  ad18
                       ad20
[root at eddie:simon] diskinfo -v /dev/mirror/gmd0
/dev/mirror/gmd0
        512             # sectorsize
        200049647104    # mediasize in bytes (186G)
        390721967       # mediasize in sectors

[root at eddie:simon] diskinfo -v /dev/ad18
/dev/ad18
        512             # sectorsize
        200049647616    # mediasize in bytes (186G)
        390721968       # mediasize in sectors
        387621          # Cylinders according to firmware.
        16              # Heads according to firmware.
        63              # Sectors according to firmware.

IE. the gmirror device is one sector smaller than the disk device.

-- 
Simon L. Nielsen