Conference aosg::lsm

800.0. "disaster recovery steps " by COL01::LINNARTZ () Sun Jun 01 1997 15:39

    Hi,
    
    we gotta describe the disaster recovery action for a couple of
    SAP servers db's are running in ASE env. As we're using ADSM as a
    backup tool for everything then root/(ehm swap) and usr, we only 
    have to describe the steps needed for setting up root/usr and creation
    of the needed volumes. ADSM will restore the rest.
    Current OS Version will be V3.2G, we'll have to do the same for V4.X
    in the future. 
    
    root and usr are ADVFS domain's on top of two mirrored LSM volumes.
    Let me name them rz0 and rz1 for simplicity, in real life they're 
    on different controllers.
    
    I also don't want to get to much into the additional planning details
    like description of activities, used and number of media types,
    location where to put those etc.
    
    We intend to use vdump to save the FS in question.
    We also assure that the backups have additional description available
    like Hardware configuration and Console output
    use, configuration and layout of filesystems,
    existing disklabels 
    sys_check output and what Software including version/revision is
    running.
    
    We would like to have the new hardware configured the same as the
    original, but as we got the listings mentioned above but as a minimum
    we require sufficent storage to backup all data and the tape being 
    of the same family as teh one being used for dumping
    
    I'll now describe the step's i thnk are needed to get the system up
    again. If somebody knows better way's, I'll appreciate to hear about
    As I don't have a machine to check, I'll hope all commands are right,
    I'll have to verify if I can get my fingers on a spare machine
    
    - check console output and select devices. 
    - check revisions of the devices, if needed upgrade to the requested
      versions (mainly due to ASE)
    - boot OS CD of OS you're installing (same OS mainly due to ADVFS SMP
      diff's)
    - select system management option. Create device entries needed (cd
      /dev; ./MAKEDEV rz0 rz1 tz0)
    - create default disklabel for rz0 (disklabel -rw rz0 rz29)
    - create ADVFS domain/fileset (mkfdmn -r -t rz29 /dev/rz0a root_domain,
      mkfset root_domain root)
    - mount root domain (mount -t advfs root_domain#root /mnt)
    - restore FS (vrestore -x -D /mnt)
    - Convert disklabel to ADVFS (disklabel -r /dev/rrz0a > /tmp/rz0_label.sav
      disklabel -t advfs -r -R /dev/rrz0a /tmp/rz0_label.sav rz29)
    - check 
      /mnt/etc/fstab (root_domain#root / advfs rw 1 1), 
      /mnt/etc/syscobfigtab, (lsm_rootdev_is_volume = 0)
      /mnt/sbin/swapdefault  (link to /dev/rz0b)
      /mnt/etc/fdmns/root_domain (link to rz0a)
      Those checks are needed as the restauration would have restored 
      the original LSM rootvol values, and I guess the fastest way is to
      restore it to an normal advfs domain and rencapsulate it afterwards.
    ********* thing I'm uncertain about ***********
    - do I have to comment/remove the /mnt/sbin/inittab lsm entries
    - do I have to remove things under /etc/vol
      I can't use volXXX commands here, and I would think that for a
      clean reboot the changes made above are sufficent, but if it would
      ease the encapsulation of .root, I would already remove things here.
    - if /usr will also be on the disk
      I don't want to restore it right here, as I want to see LSM mirrored
      being up first. If we fail with the mirror task, w have to start over
      again, and by this the restoration of /usr would be a waste of time.
      disklabel -e and replace "unused" with "BSD4.1" in partition g. 
      Check that if root/swap are contiguous thatthere are 2 "unused
      partitions avail, in case of not being contigous, there has to be 
      3 "unused" partition needed for encapsulation process. I hope that
      the BSD4.1 will reserve the g partition for later use of /usr
    ******************** end *******************
    - boot restored disk into single user
    ****************** start *******************
    - as all the volume configuration info is useless at this point (all
      disks are empty labeled at best) I would like to perform just
      - hostname <XXXX>
      - volinstall       (should fail as devices are already there)
      - vold -m disable  ( enable commands to talk to Mr. kernel)
      - voldctl init     ( init volboot as the saved info is useless)
      - voldg init rootdg ( init the dg needed for root/swap)
              I guess I have to remove the rootdg first, that's why i asked
              above if it's worthwhile to remove things before)
    
    - or would it be better to
      - voliod set 2
      - vold -m disable -r reset  ( enable talking to Mr kernel and reset
                                    it's current state)
      - voldctl init     (init volboot)
      - voldctl list     (make sure noone's there)
      - voldctl add disk rz0
      - if inittab entry was commented, uncomment that vold is started by
        default
    ******************* end ******************
    - encapsulate root_domain#root   (volencap rz0)
    - /sbin/shutdown -r +1  (boots twice and performs the filechanges)
    - add the rz1 disk for mirroring (voldctl add disk rz1)
    - assure all labels are of type "unused" (disklabel -wr rz1 rz29)
    - volrootmir rz1
    - reboot system and check that mirroring works and that all references
      point to the volumes (fstab,swapdefault, fdmns, sysconfigtab)
    - shutdown system, set bootdef_dev path and check that both are
      bootable (have valid config entries stord on disk)
    - boot and follow manual to restore /usr
    - run script to configure additional volumes needed 
    
    
    
    Sorry if my questions are obvious, but I ddin't find this scenario 
    being covered in the Appendix B in V1.2A manual nor in the V4.0
    manuals. Simple reinstalling the OS would also be a way, but then 
    you would have to add all patches, and all setup data. In my view 
    this takes far more time, and it's not what the customer understands
    by restoring a backup. I just want to save the time of trying all the
    various scenarios, but as already said, if you know better way's
    I would love to hear about.
    
    thanks in advance
     Pit