/boot on RAID1: "Can't open /boot"

I've tried to follow the instructions in "Chapter 15.
NetBSD RAIDframe" 
for booting NetBSD from RAID1.

My configuration is NetBSD 3.1 over 4 250 GB SATA drives
configured with:
  RAID1 root partition (mirroring across all 4 disks)
  RAID5 large partition (spanning all 4 disks)

The error I'm getting when trying to boot the system is:
Boot failed (errno  2): Can't open /boot

I thought the main tricks were:
 * make sure there's a partition visible with fdisk and
marked active
 * make sure / is only RAID1 (since RAID5 not supported for
root 
filesystem at boot time)
 * make sure / starts at the beginning of the RAID
partition
 * make sure RAID is configured to set "root" and
"autoconfig" (-A root)
 * run installboot for all bootable disks
 * based on the error message, I've double-checked the
"/boot" file and 
ensured it is the same as in /usr/mdec

I can boot off a CD and mount the RAID partitions so I know
RAID is 
working and the filesystems are ok.

Is there something I'm missing or anything else I should
try?  Are there 
any peculiarities with RAID1 mirroring across all 4 disks
instead of just 2?

Thanks,
Mike

On Fri, Aug 24, 2007 at 10:25:19PM -0600, Mike Frandsen
wrote:
> I've tried to follow the instructions in "Chapter
15. NetBSD RAIDframe" 
> for booting NetBSD from RAID1.
> 
> My configuration is NetBSD 3.1 over 4 250 GB SATA
drives configured with:
>  RAID1 root partition (mirroring across all 4 disks)
>  RAID5 large partition (spanning all 4 disks)
> 
> The error I'm getting when trying to boot the system
is:
> Boot failed (errno  2): Can't open /boot
> 
> I thought the main tricks were:
> * make sure there's a partition visible with fdisk and
marked active
> * make sure / is only RAID1 (since RAID5 not supported
for root 
> filesystem at boot time)
> * make sure / starts at the beginning of the RAID
partition
> * make sure RAID is configured to set "root"
and "autoconfig" (-A root)
> * run installboot for all bootable disks
> * based on the error message, I've double-checked the
"/boot" file and 
> ensured it is the same as in /usr/mdec

Seems about right.
 
> I can boot off a CD and mount the RAID partitions so I
know RAID is 
> working and the filesystems are ok.
> 
> Is there something I'm missing or anything else I
should try?  Are there 
> any peculiarities with RAID1 mirroring across all 4
disks instead of just 2?

Not relevant to the boot code, it doesn't actually know
anything about
the raid setup, it has a 'hack' to look an additional 64
sectors down
the disk for the root filesystem.

	David

-- 
David Laight: davidl8s.co.uk

Mike Frandsen writes:
> I've tried to follow the instructions in "Chapter
15. NetBSD RAIDframe" 
> for booting NetBSD from RAID1.
> 
> My configuration is NetBSD 3.1 over 4 250 GB SATA
drives configured with:
>   RAID1 root partition (mirroring across all 4 disks)
>   RAID5 large partition (spanning all 4 disks)
> 
> The error I'm getting when trying to boot the system
is:
> Boot failed (errno  2): Can't open /boot
> 
> I thought the main tricks were:
>  * make sure there's a partition visible with fdisk and
marked active
>  * make sure / is only RAID1 (since RAID5 not supported
for root 
> filesystem at boot time)
>  * make sure / starts at the beginning of the RAID
partition
>  * make sure RAID is configured to set "root"
and "autoconfig" (-A root)
>  * run installboot for all bootable disks
>  * based on the error message, I've double-checked the
"/boot" file and 
> ensured it is the same as in /usr/mdec
> 
> I can boot off a CD and mount the RAID partitions so I
know RAID is 
> working and the filesystems are ok.
> 
> Is there something I'm missing or anything else I
should try?  Are there 
> any peculiarities with RAID1 mirroring across all 4
disks instead of just 2?

Yes.  A RAID 1 set across 4 disks isn't a 4-way mirror (like
it 
should be).  It's a interleaved mirror, which means that
some of 
/boot may be one one disk, and the rest on another disk (or
it might 
be all on one or the other).  Once /boot gets split up (or
is all on 
the disk that you didn't boot from), the initial boot code
doesn't 
have a clue where to find all of it..

Stick with 2 disks and you should be fine...

Later...

Greg Oster

BTW, software RAID-5 seems scary.  search for threads about
UPS and
read/writeback.  I'd get two x 750 and RAID-1 the whole
thing.

  Are there any peculiarities with RAID1 mirroring across
all 4 disks
  instead of just 2?

That's possible; everyone else just uses 2.  My 3.1
raidframe system is
2 x 400G with the entire disk RAID1.

But, the book code just sees a partition of type RAID, and
skips 64
sectors, so it won't know how many copies.

Can you explain your partitioning in more detail?  I would
expect (on
each disk) that you have a single fdisk partition of type
169 for the
whole disk (63-$), and within that a NetBSD disklabel (with
d 0-$, c
63-$).  I'd expect a (63-1G or so), and e (after a to end). 
Both a and
e would be type RAID.  Within raid0, a disklabel with only
partition a,
from 0-$.  Within raid1, a disklabel with only b, e, f, ...,
starting at
0, continguous.  raid0 would be autoconfigured with root,
raid1
autoconfigured without root.  Or perhaps swap is in the
RAID-1.

I haven't read the boot code.  See

  src/sys/arch/i386/stand/bootxx/boot1.c

search for RF_PROTECTED.