Change out OS disks in large database system (2nd Attempt)

[Philip Kernohan]

Scenario:

Large server connected via 8 FCs to disk array which has a Oracle database residing on it.

OS disks are currently 4GB and located in a mini-disk array separate from the larger array.

We need to move the OS from the non-mirrored 4GB drives (bad planning I know) to mirrored 18 GB drives.

We have to ensure that all of the database remains intact and hence all the devices etc. that Unix sees remain the same in the large disk array to allow the Oracle datafiles to function.

Tried using Ignite but this failed as apparently there is not enough space to display the list of 800+ devices so that we can choose which new 18 GB drives to place the OS on. In short, when we Ignite from the tape we need to change the disk location for the OS, Ignite does some form of device query, finds 800+ devices and then fails as this list is too big to hold in the space it has allocated to display the list via the TUI.

Therefore I think we're ready to try plan B - is it entirely possible to do the following:

1) fbackup OS
2) Power down, remove 4 GB, insert 18 GB
3) Power up, install UX
4) Recover OS from fbackup
5) Reboot ... will all device names now be the same and therefore should all of the VGs, LVs be good to go?

If this WILL NOT work are there better methods for backup and recovery outside of Ignite.

All help appreciated.

Regards,
PK

[A. Clay Stephenson · Accepted solution]

Hi:

There is no assurance that the device names will be the same especially if cards have been added/deleted since the original OS was installed. I would be tempted to disconnect some devices and try your Ignite again. After your system has booted, shutdown and reconnect the 800+ devices.

[Scott Van Kalken]

If you're not willing to do an ignite restore, I would:

take a full ioscan
take a full lsdev
save the /stand/system
save the kernel
save all files in /etc/
vgcfgbackup all volume groups (I have attached a small script to do this)

I would also reccommend disconnecting everything except core hardware.

ensure that all device names are the same, change them if necessary to the old names as per your printed oiscan output.

Install drivers as necessary as per the lsdev output.

Attach devices with multiple reboots, continue until all devices are installed.

Now comes the interesting bit.

do another lsdev and ioscan on the "new" system.

diff the old ioscan and lsdev against the new ones.

If they're the same, attempt to restore the vgcfgbackup.

I would however not do anything like this unless you'd had a run through attempt on another machine first. This can get very messy very quickly.

Ignite is easier.

[Philip Kernohan]

Many thanks for the prompt responses ...

Sounds like:
- shutting down Oracle
- umounting any LVs (some filesystems there also outside of vg00)
- disabling the VGs
- disconnecting the FCs (labelled!)
- take the Ignite backup
- shutting down
- removing the 4GBs, inserting the 18GBs
- reboot for Ignite
- choose OS disk
- install Ignite image and boot up
- insert FCs
- enable VGs
- mount LVs

would actually be easier. Does anyone foresee any additional shutdowns required amongst that operation?

Regards,
Philip

[Scott Van Kalken]

Since you're playing around with hardware etc....

I would also disable the startup of all oracle databases BEFORE you take the ignite.

This will mean on a restored system, they will not start automagically... just to be on the safe side... but I'm possibly overly cautious.

[Byron Myers]

clay's suggestion is the way to go. I believe you will run into the same problem if you cold install HP-UX - with too many devices attached to the system. Just connect the one path to the disk to ignite, leave all other paths disconnected. After the Ignite install reboots the system, interrupt the boot, connect all of your devices and you should be good to go.