I've been dealing with this at an unusually high frequency these days.
It's even dodgier on SPARC. My recipe has been to run format -e and
first try to label as SMI. Solaris PCs sometimes complain that the disk
needs fdisk partitioning and I always delete *all* partitions, exit
fdisk, enter fdisk again, at which time it prompts me to make it a 100%
Solaris partition and I agree. I think that may have been my way of
accomplishing the part where you bailed and did your Linux partition
hacking, Frank. Anyway, after that, remember that you currently still
have to use SMI labels for the root pool, so run label and choose that.
format(1M) sometimes momentarily hangs and crashes the there, iirc --
if this happens to you, run it again and it's fine the second time
through. Maybe related to fdisk changes plus RAM disklabel vs on-disk
disklabel, etc. Anyway, make slice 0 identical to slice 2, which is
congruent with the OpenSolaris install procedure; however to eliminate
human error, a
prtvtoc /dev/dsk/cXtXd0s0 | fmthard -s- /dev/rdsk/cXtXd0s0
should work for you, at this point, to duplicate the label from the
first disk to the second. Read and understand that command before
issuing it as it does very little second guessing and can easily nuke
stuff if you run it wrong.
Note: on SPARC, if you're using generic disks that happen to be the same
part numbers as real Sun disks, but have generic labels instead of the
nice "SUN146G" and the like, you can run into this issue of ZFS refusing
to mirror to a smaller disk again. My solution to that was to run
format => type and select the type matching the other disk, then
continue such that all reasonably matching disks have the same type.
This seems to help with geometry issues and also completely changed
(drastically for the better) the performance characteristics of some
disks in my SunFire v440.
*Note to others who may end up here later or for tangential reasons:
Realise that pretty much all of these gross manipulations of your disk
configuration are sufficiently heavy-handed that you're going to lose
everything stored on the disk in question when you run them.
hth
jake
Frank Middleton wrote:
On 06/04/09 06:44 PM, cindy.swearin...@sun.com wrote:
Hi Noz,
This problem was reported recently and this bug was filed:
6844090 zfs should be able to mirror to a smaller disk
Is this filed on bugs or defects? I had the exact same problem,
and it turned out to be a rounding error in Solaris format/fdisk.
The only way I could fix it was to use Linux (well, Fedora) sfdisk
to make both partitions exactly the same number of bytes. The
alternates partition seems to be hard wired on older disks and
AFAIK there's no way to use that space. sfdisk is on the Fedora
live CD if you don't have a handy Linux system to get it from.
BTW the disks were nominally the same size but had different
geometries.
Since I can't find 6844090, I have no idea what it says, but this
really seems to be a bug in fdisk, not ZFS, although I would think
ZFS should be able to mirror to a disk that is only a tiny bit
smaller...
-- Frank
I believe slice 9 (alternates) is an older method for providing
alternate disk blocks on x86 systems. Apparently, it can be removed by
using the format -e command. I haven't tried this though.
I don't think removing slice 9 will help though if these two disks
are not identical, hence the bug.
You can workaround this problem by attaching a slightly larger disk.
Cindy
noz wrote:
I've been playing around with zfs root pool mirroring and came across
some problems.
I have no problems mirroring the root pool if I have both disks
attached during OpenSolaris installation (installer sees 2 disks).
The problem occurs when I only have one disk attached to the system
during install. After OpenSolaris installation completes, I attach the
second disk and try to create a mirror but I cannot.
Here are the steps I go through:
1) install OpenSolaris onto 16GB disk
2) after successful install, shutdown, and attach second disk (also
16GB)
3) fdisk -B
4) partition
5) zfs attach
Step 5 fails, giving a "disk too small" error.
What I noticed about the second disk is that it has a 9th partition
called "alternates" that takes up about 15MBs. This partition doesn't
exist in the first disk and I believe is what's causing the problem. I
can't figure out how to delete this partition and I don't know why
it's there. How do I mirror the root pool if I don't have both disks
attached during OpenSolaris installation? I realize I can just use a
disk larger than 16GBs, but that would be a waste.
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