Hi Frank,
This bug was filed with bugster, but I see that the opensolaris bug
database is currently unavailable. I sent a note about this problem.
When a root cause is determined for 6844090, then we'll see whether
this particular issue is a ZFS problem or a format/fdisk problem.
In any case, improvements in this area are being discussed.
ZFS brings us light years ahead in terms of ease of use, but crappy
disk format/label/slice stuff brings us back. I just want to use
disks, I don't want to know them intimately. Why do I have to?
Cheers,
Cindy
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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