Subject: Re: RAID-1 and crash dumps
To: Greg Oster <email@example.com>
From: Manuel Bouyer <firstname.lastname@example.org>
Date: 02/04/2004 21:08:00
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
> - 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 <email@example.com>
NetBSD: 26 ans d'experience feront toujours la difference