Subject: Re: RAID-1 and crash dumps
To: Manuel Bouyer <email@example.com>
From: Greg Oster <firstname.lastname@example.org>
Date: 02/04/2004 14:17:09
Manuel Bouyer writes:
> 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 ?
Always at block 64 (or whatever RF_PROTECTED_SECTORS is #define'ed
> > 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 :)