Mirror/UX

[Sreejith Kaliyam]

If System is booted thru Primary disk which is mirrored to Secondary. In case Primary Disk fails, can system work with secondary disk?
In this case if Primary disk is removed from working system, will system be functional with Secondary disk till I replace defective primary disk?

[Santosh Nair_1]

If you've created the root mirror as a bootable drive, i.e. did a pvcreate -B and mkboot on the disk, and have mirrored everything in the proper order, i.e. /stand first, followed by swap and then everything else, then yes, you should be able to boot off the mirror disk. You will have to boot without quorum, i.e. pause the boot sequence, specify the mirror as the boot path, interact with the ISL and finally enter hpux -lq at the ISL> prompt. You need to do this because otherwise the system will look for both parts of the mirror disk.

Hope this helps.

-Santosh

[melvyn burnard]

If all your mirroring is done correctly, then yes, once the system is booted if you lose the Primary disc, provided there is nothing that will cause the bus to hang, and the mirror disc is preferably on a different i/o card, your system should continue to run.
Once you replace the defective disc, folow the correct procedures to "revive" the primary.
If you do have to reboot with the primary disc yet repaired, remember to boot to the secondary path, and with -q n option

[Helen French]

hey,

yes you can ! do this:

1) interrupt the normal boot sequence
2) boot through the secondary disk path to get ISL prompt
3) give 'hpux -lq'

this will work only if it's a pure HDD failure. ie. if u have a controller/SCSI bus error u need to look in to that. You can contninue working with the secondary disk till u replace the defective one

HTH,
Shiju

[Wodisch]

Hello Neil,

the trick really is to use
mkboot -a "hpux -lq! on BOTH raw-disks, to make them both able to boot without the other one (a VG needs more than 50% of its disks to be activated - one out of two is only 50%).

HTH,
Wodisch

[Sreejith Kaliyam]

If failure of primary disk occurs on running system and both disks are internal on same controller, then what would be the solution?

[Santosh Nair_1]

If one of the two root mirrors dies while the system is running, you should see errors in /var/adm/syslog/syslog.log, but the system should continue to run as normal (again this is assuming that all the mirrors are set up correctly).

For greater redunancy, you should probably move the root mirror to a different controller.

-Santosh

[Animesh Chakraborty]

Hi Desai,
I faced same problem few days back.The primary hard disk was faulty and my system was running fine with secondary disk until I saw the message in syslog and got it replaced.