On Tue, Jan 06, 2009 at 01:24:17PM -0800, Alex Viskovatoff wrote: > a...@diotiima:~# installgrub -m /boot/grub/stage1 /boot/grub/stage2 > /dev/rdsk/c4t0d0s0 > Updating master boot sector destroys existing boot managers (if any). > continue (y/n)?y > stage1 written to partition 0 sector 0 (abs 16065) > stage2 written to partition 0, 267 sectors starting at 50 (abs 16115) > stage1 written to master boot sector > a...@diotima:~#
> So installgrub writes to partition 0. How does one know that those > sectors have not already been used by zfs, in its mirroring of the > first drive by this second drive? Because this is a VTOC label partition (necessary for Solaris boot), I believe ZFS lives only within slice 0 (I need to verify this). So VTOC cylinder 0 is free. > And why is writing to partition 0 even necessary? Since c3t0d0 must > contain stage1 and stage2 in its partition 0, wouldn't c4t0d0 already > have stage1 and stage 2 in its partition 0 through the silvering > process? I doubt that all of partition 0 is mirrored. Only the data under ZFS control (not the boot blocks) are copied. Do not confuse the MBR partition 0 (the "Solaris partition") with the VTOC slice 0 (the one that has all the disk cylinders other than cylinder 0 in it and that appeared in your earlier "label" output). > I don't find the present disk format/label/partitioning experience > particularly unpleasant (except for grubinstall writing directly into > a partition which belongs to a zpool). I just wish I understood what > it involves. Partition 0 contains all of Solaris. So the OS just needs to keep things straight. It does this with the VTOC slicing within that partition. > Thank you for that link to the System Administration Guide. I just > looked at it again, and it says partition 8 "Contains GRUB boot > information". So partition 8 is the master boot sector and contains > GRUB stage1? It should probably refer to "slice 8" to reduce confusion. Boot loaders (GRUB since that's what is in use here) are simultaneously in partition 0 and slice 8. -- Darren _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
