Going back to mirrored after booting unmirrored - Solaris 10 x86

Question

Folks,
On one of my Solaris 10 x86 servers at the last reboot it failed to come up. I put back the versions of /etc/vfstab and /etc/system from before the boot drive was mirrored. "metastat" still reports the md versions of the slices are still in sync but I'm not convinced that's accurate since the failed reboot.
How do I go back to mirrored again at the next boot?
I've been reading doc 819-2789 "x86: How to Create a RAID-1 Volume From the root ..." and it looks like I need to go through most of the steps.
My best guess goes something like this -
Loop for each mounted slice - Use metadetach to remove the one not mounted. Use metaattach to add it back. Use metasync to confirm the mirror synced up again.
Once that loop has completed assume that any MBR stuff is broken. A bit like I've done with "mkboot" on SPARC but following the steps in the doc. Look at menu.lst, fdisk, installgrub, metaroot, have with and without mirror copies of /etc/vfstab and /etc/system ready just in case, reboot.
Basically all of the steps from the doc only instead of using metainit use metadetach, metaattach, metasync.
Does this make sense? It parallels stuff I've done on SPARC but I have a lot more experience on SPARC than on X86.
Thanks in advance, Doug Freyburger

Answer 1

freyburgerd wrote:
Folks,
On one of my Solaris 10 x86 servers at the last reboot it failed to come up. I put back the versions of /etc/vfstab and /etc/system from before the boot drive was mirrored. Exactly how you did that may matter.
"metastat" still reports the md versions of the slices are still in sync but I'm not convinced that's accurate since the failed reboot.You're absolutely correct. As soon as you write (or mount read/write) to one of the raw slices or to one of the sides of the mirror, the mirror will be out of sync, and SVM will not realize it.
How do I go back to mirrored again at the next boot?Detach the side you're not booted from. Redo the metaroot and come up on the (now one-way) mirror. Once booted from the mirror, reattach the other side.
My best guess goes something like this -
Loop for each mounted slice - Use metadetach to remove the one not mounted. Use metaattach to add it back. Use metasync to confirm the mirror synced up again.You'll want to detach before using the mirror again, but you can't attach until you stop using the raw slice. So you can't just detach/attach in one step. You'll need to reboot between them.
Once that loop has completed assume that any MBR stuff is broken. A bit like I've done with "mkboot" on SPARC but following the steps in the doc. Look at menu.lst, fdisk, installgrub, metaroot, have with and without mirror copies of /etc/vfstab and /etc/system ready just in case, reboot.
Not sure why any MBR stuff would have been affected unless you did so explicitly.
Basically all of the steps from the doc only instead of using metainit use metadetach, metaattach, metasync.
Does this make sense? It parallels stuff I've done on SPARC but I have a lot more experience on SPARC than on X86.Should be the same on both. If you're adding a new disk, you need to make sure boot support is added. But in this case I doubt any of the boot support was damaged (depending on the details of what led up to your changes).
Darren