On Wed, Feb 04, 2004 at 01:41:51PM -0600, Greg Oster wrote:
> Here's how things are setup for a partition marked as "RAID" in a 
> disklabel:
>  - 64 blocks are "reserved" via RF_PROTECTED_SECTORS.
>  - at block 32 in the reserved space is where RAIDframe hides its 1 
> block that is the component label
>  - the size of the data portion that RAIDframe will report as the 
> size of raid0d (or raid0c) is based on the largest multiple of the 
> stripe size used for a RAID set. 

And will the data portion always start at block 64, or will it be rounded
to a stripe size too ?

> 
> Say wd0e is marked as type RAID, and it's for a RAID 1 set with a 
> stripe width of 128.  If the size of wd0e is 1024 blocks, then:
>   
>   the RAID data will start at block 64 of wd0e.
>   (1024-64)/128 = 7.5  
>   the 7.5 will get rounded down to 7, and thus the data portion
>   of that component would be just 7*128=896 blocks.
> 
> If the size of wd0e is 16777216 blocks, then:
> 
>   the RAID data will start at block 64 of wd0e
>   (16777216-64)/128 = 130175.5
>   Total data portion is 130175*128 = 16777088 blocks
> 
> I'm not sure where the "96" is coming from, but it's likely related 
> to the size of the partitions...

And stripe size. I use stripe size smaller than 128, usually 64 sectors.
Looks like I've been lucky with my way of doing this :)

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--