Re: bsdinstall guided partitioning should 4k-align swap and ufs partitions

On 12/05/11 10:47, Poul-Henning Kamp wrote:
> In message <201112051743.13483.Mark.Martinec+freebsd_at_ijs.si>, Mark Martinec wri
> tes:
>> Using a guided partitioning install of 9.0-RC2 on a 64GB (virtual) disk
>> (from a 9.0-RC2 ISO image) results in the following GPT partitioning:
>>
>> # gpart show /dev/ada0
>> =>       34  134217661  ada0  GPT  (64G)
>>         34        128     1  freebsd-boot  (64k)
>>        162  125828992     2  freebsd-ufs  (60G)
>>  125829154    6709248     3  freebsd-swap  (3.2G)
>>  132538402    1679293        - free -  (820M)
>>
>> This is most unfortunate for installations using 4kB sectored disks
>> or SSD disks, [...]
> 
> This is not a new problem, you face the same issue with RAID5 devices.
> 
> 
> GEOM defines two provider properties for handling all these cases
> correctly: stripesize + stripeoffset.
> 
> If the disk-driver has a 4k drive, or suspects it has a 4k drive (
> these properties are advisory only), it should announce that with
> the stripe* properties on its GEOM provider.
> 
> GEOM classes are responsible for passing these properties up with
> whatever adjustments are necessary (for instance modifying the
> stripeoffset for partitions).
> 
> The partitioning tools, (All of them!) should examine these two
> properties and prod the user towards not doing something silly.
> 

The installer will align all partitions to the GEOM stripesize/offset.
We could make it do min(4KB, stripesize), but in general I think this is
better done at the GEOM level.
-Nathan