topic Re: Replacing a boot disk with LVM in Operating System - HP-UX

Replacing a boot disk with LVM

KURT HARLESS — Wed, 12 Sep 2001 19:40:15 GMT

Greetings,

Have I/O read errors on my disk c2t6d0. HP is coming out to replace tonight.
This disk participates in VG00 which has 4 physical disks, c2t3d0 thru c2t6d0. VG00 has 9 LVOLs;
------LVOLS---- --FS------ MIRROR -ALLOC-
/dev/vg00/lvol1 /stand 1 strct/cont
/dev/vg00/lvol2 swap/dump 1 strct/cont
/dev/vg00/lvol3 / 1 strct/cont
/dev/vg00/lvol4 /tmp 1 strict
/dev/vg00/lvol5 /home 1 strict
/dev/vg00/lvol6 /opt 1 strict
/dev/vg00/lvol7 /usr 1 strict
/dev/vg00/lvol8 /var 1 non-strict
/dev/vg00/lvol9 /u09 0 non-strict

# lvlnboot -v /dev/vg00
Boot Definitions for Volume Group /dev/vg00:
Physical Volumes belonging in Root Volume Group:
/dev/dsk/c2t3d0 (10/0.3.0)
/dev/dsk/c2t5d0 (10/0.5.0)
/dev/dsk/c2t6d0 (10/0.6.0) -- Boot Disk
/dev/dsk/c2t4d0 (10/0.4.0) -- Boot Disk
Boot: lvol1 on: /dev/dsk/c2t6d0
/dev/dsk/c2t4d0
Root: lvol3 on: /dev/dsk/c2t6d0
/dev/dsk/c2t4d0
Swap: lvol2 on: /dev/dsk/c2t6d0
/dev/dsk/c2t4d0
Dump: lvol2 on: /dev/dsk/c2t6d0, 0

Questions:

1) I have emptied LVOL9 and plan on removing it from the volume group. Would it be better to first replace the disk then remove it, or should I remove it, run a vgcfgbackup, replace the disk, then vgcfgrestore.

2) When you remove a lvol, do you have to manually remove the entries from fstab and mnttab?

3) Since c2t6d0 is my primary boot disk, and if I read the lvlnboot above correctly, c2t4d0 is my secondary, do I have to recreate this after replacing the disk, or does the vgcfgrestore rebuild this configuration.

4) If I need to make this a boot disk again, how?

Nervous in Phoenix...

Kurt

Re: Replacing a boot disk with LVM

James R. Ferguson — Wed, 12 Sep 2001 20:21:55 GMT

Hi Kurt:

The following procedure applies:

# Shutdown your system and replace the disk that is failing.

# Boot into single user mode and override the quorum, as:

# ISL> hpux -is -lq /stand/vmunix

# vgcfgrestore -n /dev/vg00 /dev/rdsk/cXtYdZ

# mkboot /dev/rdsk/cXtYdZ

# mkboot -a "hpux -lq /stand/vmunix" /dev/rdsk/CXtYdZ

# lvlnboot -R

# lvlnboot -v #...to verify all is as desired...

# vgchange -a y /dev/vg00

# vgsync /dev/vg00

# shutdown -ry 0

With regard to your other questions:

(1) I'd wait until your reconstruction is complete before removing "lvol9". The less LVM maintenance done while your configuration is brittle, the better.

(2) You will manually remove the "lvol9" mountpoint from /etc/fstab. You do not modify /etc/mnttab. This occurs naturally as a consequence of mounting and unmounting filesystems.

(3/4) The 'lvlnboot -R' updates the BDRA of each bootable disk.

Regards!

...JRF...

Re: Replacing a boot disk with LVM

Byron Myers — Wed, 12 Sep 2001 20:26:56 GMT

1. either way is fine. This is an independent task from replacing a disk.
2. Yes, you need to remove the associated entry in fstab.
3 & 4). To replace a mirrored boot disk:
# vgcfgrestore -n /dev/vg00
# mkboot /dev/rdsk/
# mkboot -a "hpux (;0)/stand/vmunix" /dev/rdsk/
# lvlnboot -R

For older systems, you need to be in single user mode to do this - booted with no disk quorum:
reboot
interrupt boot sequence
interact with ISL
ISL> hpux -is -lq /stand/vmunix

I believe the you can hot-swap boot disks in the newer N's and L's.

Re: Replacing a boot disk with LVM

KURT HARLESS — Wed, 12 Sep 2001 20:55:35 GMT

These forums and your answers are awesome!

One additional dumb question;

What is the difference between /dev/dsk & /dev/rdsk ?

Thanks again, not sooooo nervous in Phoenix

Kurt

Re: Replacing a boot disk with LVM

Sanjay_6 — Wed, 12 Sep 2001 21:00:17 GMT

Hi Kurt,

Like the other have already said,

1.) Remove the lvol9 after your disk change and things are over.

2.) you have to manually edit /etc/fstab and remove the entry corresponding to lvol9

3.) after replacing the disk, boot using your second boot disk, say it is set as alt boot path
bo alt 'or' bo
boot in single user mode overiding the quorum.
ISL> hpux -is -lq (;0)/stand/vmunix
vgcfgrestore -n /dev/vg00 /dev/rdsk/c2t6d0
mkboot /dev/rdsk/c2t6d0
mkboot -a "hpux (;0)/stand/vmunix" /dev/rdsk/c2t6d0
lvlnboot -R

Reboot the box, again reboot using your second disk
bo alt
Do vgsync to syncronise the data
vgsync /dev/vg00
Then reboot again using c2t6d0.

If you are trying to do vgsync in single user mode at the first boot, you have to manually mount the rest of the filesystems, i think.

Hope this helps

Thanks

Re: Replacing a boot disk with LVM

Sanjay_6 — Wed, 12 Sep 2001 21:04:09 GMT

Hi Kurt,

/dev/dsk refers to the block device , /dev/rdsk refer to the character device or the raw device.

Hope this helps.

Thanks

Re: Replacing a boot disk with LVM

KURT HARLESS — Thu, 13 Sep 2001 00:11:30 GMT

Thanks to everyone, the operation was a complete success.

Kurt