which disk is system running from?

[Rick Garland]

Hi all:

Got a rp7410 running 11.11.
I have been told that the system is currently running off the alternate boot disk. How can I tell?

I have looked at the info from the kernel and the output is telling me that the system booted from the primary boot disk, the lvlnboot info is correct, the setboot info is correct, etc. The system has been up over 3 months now but the previous sysadm is telling me that the system is running off the alternate boot disk. It did a fail over to the alternate boot disk during 4th of July. But system didn't crash - doesn't system need to bounce to boot/run off the alternate boot disk? Again, how can I verify?

Many thanks!
Rick

[Steven E. Protter · Accepted solution]

lvlnboot -v

That will tell you configuration and the way its currently booted.

SEP

[Richard Pereira_1]

With a good mirror, you dont need to crash reboot to switch over to the mirror.

first, try this to determine which disk your kernel last booted.
# echo 'boot_string/S'|adb /stand/vmunix /dev/mem

then run lvlnboot -v to get the 2 disk device names, then run pvdisplay -v on each disk and check for stale extents. If you have any, then yes , the system might have switched over, else your ok.

[Rick Garland]

lvlnboot is telling me that primary boot disk is 1st in list. Does this mean it is running the primary disk? If the secondary disk is running the system would lvlnboot list the secondary disk as 1st in the list?

[Richard Pereira_1]

i wouldnt trust lvlnboot, it just lists the configs, its not dynamic, try

# echo 'boot_string/S'|adb /stand/vmunix /dev/mem

[Rick Garland]

The echo boot_string is listing the primary boot disk as the disk the system booted from.

[Geoff Wild]

Richard has it:

echo 'boot_string/S'|adb /stand/vmunix /dev/mem

lvlnboot -v /dev/vg00

justs prints information on root, boot, swap, and dump logical volumes.

Example, on mine:

# echo 'boot_string/S'|adb /stand/vmunix /dev/mem
boot_string:
boot_string: disk(1/0/0/3/0.6.0.0.0.0.0;0)/stand/vmunix

Yet:

lvlnboot -v /dev/vg00
Boot Definitions for Volume Group /dev/vg00:
Physical Volumes belonging in Root Volume Group:
/dev/dsk/c28t5d0 (0/0/0/3/0.5.0) -- Boot Disk
/dev/dsk/c0t6d0 (1/0/0/3/0.6.0) -- Boot Disk
Boot: lvol1 on: /dev/dsk/c28t5d0
/dev/dsk/c0t6d0
Root: lvol3 on: /dev/dsk/c28t5d0
/dev/dsk/c0t6d0
Swap: lvol2 on: /dev/dsk/c28t5d0
/dev/dsk/c0t6d0
Dump: lvol2 on: /dev/dsk/c0t6d0, 0


Second disk listed in lvlnboot is where I booted from.

Try not to think of having a primary/secondary disk - think of it as 2 disks mirrored - both are identical.

Rgds...Geoff

[A. Clay Stephenson]

Probably the best bet is to ask the kernel itself:

echo "boot_string/s" | adb /stand/vmunix /dev/kmem

That will tell you which disk the system actually booted from but it won't tell you which disk the the system is actually using because the answer is probably both -- with reads being satisfied from either mirror and writes being written to both.

If the primary boot disk fails the system will happily continue to run using the mirrored LVOLS. You can then replace the primary boot boot and as long as you carefully follow the mirrored boot disk replacement steps there is no need to shutdown. I have not shutdown to replace a disk (including boot and boot alternates) in well over 5 years.

[T G Manikandan]

The best way to confirm is using

#echo 'boot_string/S'|adb /stand/vmunix /dev/mem

[Fabio Ettore]

Hi,

as Richard said the right command to verify what is the last boot disk is

# echo 'boot_string/S'|adb /stand/vmunix /dev/mem

You will obtain the hw path of the disk which system booted last time.
It is important that 'echo boot_string...' and 'lvlnboot' have the same info but I saw that it's correct for you.
Also you told that setboot is correct too.

Definitively your system booted from primary boot disk.
Then how to do your sysadm says that the system is running off the alternate boot disk? What does he think that? What commands he launched to tell that?

Best regards,
Fabio

[Richard Pereira_1]

There you have it, the people have spoken! ;-)
For now it seems you booted off the primairy, but check for stale extents, check that both drives are claimed...

[Rick Garland]

Richard:

I have no doubts about what was being posted - I did all tese commands previously before I posted. My issue is that I being told something that I cannot confirm - I do not profess to know all the answers so I come here to get additional info. In this case I am correct, I do not see any questionable issues with the system boot. But I want to make sure I am not missing something else that I may not be aware of.

Many thanks to all!

[Richard Pereira_1]

No problem, you wanted to double check what the other admin told you.