fakeraid/dmraid on intel matrix RAID-0 array
Phillip Susi
psusi at cfl.rr.com
Wed Jul 16 21:47:25 UTC 2008
Greg Watson wrote:
> I've been following these guides:
> http://help.ubuntu.com/community/FakeRaidHowto
> which lead me to this page:
> https://help.ubuntu.com/community/FakeRaidDebug
> I have followed the guide, located the exact Array information sectors.
<snip>
> Before patching, dmraid told me this:
> Code:
>
> ERROR: isw: Error finding disk table slot for /dev/sdb
> ERROR: isw: Error finding disk table slot for /dev/sda
> No RAID disks
>
> I then tried patching dmraid code per the guide. So the dd copied the last
> 1024 bytes, so 1024 / 512 (per sector) = 2.
>
> After patching #define ISW_CONFIGOFFSETS in the code (isw.h) and
> recompiling, I only get.
The patching part of the guide is for pdc controllers, not Intel, since
pdc likes to throw their metadata in all sorts of odd offsets, but Intel
always goes with 2 sectors from the end. The error does not indicate
that it can't find the metadata, but that there is a problem with the
metadata it found where it can't find the part that specifically
describes that disk.
This is the result of a bug I mentioned in a recent thread entitled "Why
are spaces removed from the disk serial number?" in which I point out
that dmraid removes whitespace from the disk serial number before trying
to compare it with the serial number recorded in the metadata, which no
longer matches since it still has the whitespace. I never did get an
answer about why the whitespace is removed, and if that removal can be
disabled to fix this problem.
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