Problem Description
If your machine with an SDS-mirrored root disk has been completely destroyed
and you need to restore from backup, this document will show you the additional
steps you must take to re-create the DiskSuite state databases and how to resolve
issues with the mirrored boot configuration on your backup tapes.
This document assumes that the reader has a good working knowledge
of DiskSuite.
Problem Solution
Problem Description
If your machine with an SDS-mirrored root disk has been completely destroyed
and you need to restore from backup, this document will show you the additional
steps you must take to re-create the DiskSuite state databases and how to resolve
issues with the mirrored boot configuration on your backup tapes.
This document assumes that the reader has a good working knowledge
of DiskSuite.
Problem Solution
NOTE: In order to restore the machine exactly the way it was, it is necessary
to have a record of the locations of the state databases, and also the
configuration of the metadevices. These are *not* held in user-readable form
on the root filesystem, so it is useful to get the information BEFORE a crash
with the commands:
# metadb -i
This command shows the condition and location of DiskSuite's state database replicas. It is useful to have this information in case their recreation is neccessary.
# metastat -p
You will redirect this output to a file for safekeeping. This information is most often sent to the /etc/opt/SUNWmd/md.tab file for disaster recovery purposes (see step 6 below). Check the md.tab file prior to overwriting it, though. If a valid one exists, redirect the metastat -p to another filename and run a 'diff' on it to check for inconsistencies. The metastat -p, however, will reflect the most current, known, configuration.
Of course, you will need to create a new root disk and restore the last full backup to that new disk. It is expected that you will partition the disk in much the same manner as you had it before. Remember that if there was a small partition on your original disk for a state replica that you do the same thing for this disk.
Once the disk has been created, restore your root filesystems from backups. However, before attempting to boot the system after the restore, we must make some necessary changes to let Solaris know that the root disk is no longer mirrored. To do this, the /etc/system and the /etc/vfstab files must be modified.
1) Boot cdrom, and mount the root filesystem to /a.
ok boot cdrom -s
# mount /dev/dsk/c#t#d#s# /a
2) Restore the root filesystem from backup tape into /a and initialise the boot block using
# installboot /usr/platform//lib/fs/ufs/bootblk /dev/rdsk/c#t#d#s#
3) Mount and restore any other critical filesystems such as /usr /var /opt etc.
4) If the replacement machine does not have it disks connected via the same paths as the original then you may have to follow the procedure documented in SRDB 15010 to rebuild the /devices and /dev structures.
5) vi /a/etc/system (before using vi you may need to set the terminal type e.g. TERM=sun; export TERM)
Remove ALL lines between the "MDD root info" lines as well as those between the "MDD database info" lines. In the following example file, all these lines would be removed from the file:
-------------------------------------------------------------
* Begin MDD root info (do not edit)
forceload: misc/md_trans
forceload: misc/md_raid
forceload: misc/md_hotspares
forceload: misc/md_stripe
forceload: misc/md_mirror
forceload: drv/sd
forceload: drv/esp
forceload: drv/espdma
forceload: drv/sbus
forceload: drv/iommu
rootdev:/pseudo/md@0:0,3,blk
* End MDD root info (do not edit)
* Begin MDD database info (do not edit)
set md:mddb_bootlist1="sd:14:16 sd:15:16"
* End MDD database info (do not edit)
-------------------------------------------------------------
6) vi /a/etc/vfstab
Change all metadevices for the root filesystems (root, usr, var, and opt) back to regular slices (/dev/dsk/c#t#d#s#). Comment out all the other metadevices for the time being. For example:
** EXAMPLE FILE BEFORE:
---------------------------------------------------------------------------
#device device mount FS fsck mount mount
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