what is difference between "single user mode" and "maintenance mode"

[senthil_kumar_1]

Hi All,

what is difference between "single user mode" and "maintenance mode"

[Robert_Jewell · Accepted solution]

Nothing really, unless you are referring to LVM Maintenance Mode (by booting with hpux -lm). LVM maintenance mode does not activate VG00 (single user mode does).

"Maintenance mode" is an old term used in reference to "Single User" mode as its assumed you are going to work on the OS.

-Bob

[Pete Randall]

Virtually no difference at all. The man page for hpux says this about maintenance mode:

"-lm

Boot the system in LVM maintenancemode, configure only the root volume,and then initiate single user mode."

Since you end up in single user mode anyway, I really don't see much difference.


Pete

[sujit kumar singh]

Hi


In single user mode you cannot export the root VG which you can do only in the LVM miant mode.

regards
sujit

[Michael Steele_2]

"..."Maintenance mode" is an old term used in reference to "Single User" ...."

Wrong, wrong, wrong.

"..mode as its assumed you are going to work on the OS..."

Correct.

In fact, under the 10 and 11 O/S you can not go from maintenance mode to run level 3 without risking corruption to the O/S file systems.

You must reboot from maintenance mode.

And this is the biggest difference.

[Michael Steele_2]

Geez, I had forgotten this. LVM maintenance mode boots not from the lif, but from /etc/rootconf. This is the reason for the risk of corruption unless rebooted.

http://forums11.itrc.hp.com/service/forums/questionanswer.do?admit=109447626+1261420540100+28353475&threadId=815752

Note: And I no longer know if this is valid for Integrity.

[Pete Randall]

Michael,

Thanks for clarifying. I thought there had to be some (historical) difference but could not remember what it might be.


Pete

[Robert_Jewell]

In reply to "wrong, wrong, wrong"...

I agree that there are a good number of differences between booting "hpux -is" and "hpux -lm". However, in the authors question, he does not refer to *LMV* maintenance mode specifically. There are other operating systems that refer to single user mode as "maintenance mode", which is where why comparison to the two is as I put it. In general UNIX terms there isn't much difference. In HP-UX specific terms we know there is difference worth mentioning.

-Bob

[senthil_kumar_1]

Hi All,

LVM maintenance mode (hpux -Im) will have only root VG (/dev/vg00) and start single user mode.

But single user mode will have all VGs.

Am i correct?

[Pete Randall]

You will have to mount all the filesystems.


Pete

[Robert_Jewell]

When entering LVM Maintenance Mode none of the VG's will be active. This allows you to work on VG00.

When entering Single User Mode, you do have VG00 active, but with nothing other than / and /stand mounted.

-Bob

[Torsten.]

To be a bit pedantic, there is a

- LVM maintenance mode (-lm)
- tunable maintenance mode (-tm)
- VxVM maintenance mode (-vm)


All are different.

[Torsten.]

Regarding the LVM maintenance mode:

LVM maintenance mode boot is a special way to boot your system that bypasses the normal
LVM structures. Use it only for problems that prevent the system from otherwise booting. It is
similar to single-user state in that many of the processes that normally start do not start, and
many of the system checks are not performed. LVM maintenance mode is intended to enable
you to boot your system long enough to repair damage to the system LVM data structures
typically using vgcfgrestore, which then enables you to boot your system normally.
Normally, the boot loader uses the LABEL file in the LIF volume to determine the location of the
boot file systemand the kernel /stand/vmunix. The LABEL file also contains the starting block
and size of the root file system.
Under amaintenancemode boot, the boot loader attempts to find the boot file systemat the start
of the boot disk's user data area rather than using information from the LIF volume. To obtain
the root file system's starting block and size, the boot loader reads the file /stand/rootconf.
Since LVM is not enabled, the root file system must be allocated contiguously.
A maintenance mode boot differs from a standard boot as follows:
- The system is booted in single-user mode.
- No volume groups are activated.
- Primary swap and dump are not available.
- Only the root file system and boot file system are available.
- If the root file system is mirrored, only one copy is used. Changes to the root file system are
not propagated to the mirror copies, but those mirror copies are marked stale and will be
synchronized when the system boots normally.
To boot in maintenance mode on a system with a root disk configured with LVM, use the -lm
option to the boot loader. On an HP 9000 server, enter the following command:

ISL> hpux -lm

On an HP Integrity server, enter the following command:

HPUX> boot -lm




from
HP-UX System Administrator's Guide: Logical
Volume Management
HP-UX 1 1i Version 3

HP Part Number: 5992-4589

[Suraj K Sankari]

>>LVM maintenance mode (hpux -Im) will have only root VG (/dev/vg00) and start single user mode.

>>But single user mode will have all VGs.

Yes you are right,

Once you are login in single user mode you can mount any of the file system of your system.

Suraj

[Michael Steele_2]

RE: "...In general UNIX terms there isn't much difference..."

I have never met anyone who described Unix as 'ambiguous', like you do.

Again, wrong, wrong, wrong.

[R.K. #]

Hi Senthil,

LVM maintenance mode is used to repair damaged LVM data structures.


In single user mode, vg00 will be activated, root and stand will be mounted. Whereas in maintenance mode no vg will be activated hence nothing will be mounted.

ISL> hpux -lm

If you cannot boot your system using a maintenance mode boot, the LIF area, LABEL file, or the root file system is corrupt. You can try booting from a different disk if you have a mirror copy of the root file system somewhere. Otherwise, you will probably need to reinstall the boot information from the recovery shell, or in a worst case, by reinstalling HP-UX (hopefully from your make_net/tape_recovery image).

Do not switch to multiuser mode (Do not use the /sbin/init 2 command). You can corrupt your root file system if you do.

[Johnson Punniyalingam]

>>>LVM maintenance mode (hpux -Im) will have only root VG (/dev/vg00) and start single user mode.<<<

this mode is to perform or repair Logical Volume maintenance mode ,

>>But single user mode will have all VGs.<<

vg00 only - will be activated, but you need mount other file system like /usr

other vg's manually can also be "activate"

[T. M. Louah]

Great Input, serious feedback thx. can you go to "Maintenance mode" without reboot ? no, but you can get to single-user mode using "init" command .. or "shutdown -y 0". I think maintenance mode is for more lower-level issues e.g.: boot from specific disk or specific kernel..
T#

[Patrick Wallek]

>>can you go to "Maintenance mode" without reboot ? no,

If you are talking about LVM maintenance mode, correct! You must reboot and boot with "hpux -lm"

>>but you can get to single-user mode using "init" command .. or "shutdown -y 0".

Kind of. I don't trust this as a true single-user mode though. It's not quite the same as rebooting and starting via "hpux -is"

>>I think maintenance mode is for more lower-level issues e.g.:

Right. Specifically working with VG00 if need be.

>>boot from specific disk or specific kernel..

Not necessarily. Booting from a specific disk or booting from a backup kernel is done when you interrupt the boot process when the server is starting.