Boot from recovery CD or media to edit fstab

[TechC]

Hello ITRC members.

I have an HP-UX C200 running 10.20 that is hanging on boot due to a bad mount point in fstab. I believe this mount point is not on vg00 and thus not on the root disk.


If this were Solaris I would boot from the install media, mount c0t0d0s0 and edit vfstab to pound out the offending entries.

With HP-UX can I boot from the Install CD, run a recovery shell, mount /dev/vg00/lvol3 (/) and remove the offending entries from fstab?

Please provide the steps if possible. I can boot from the CD and get to the recovery shell but not sure how to mount the lvols.

Also I think the answer to this next question is no, but can I pull a disk from c360 and put it in a c200? I seem to remember the disks being different scsi standards one is FW and one is ultra wide I think.
Thank you in advance.

James

[Analyst]

Hi,

1. Reboot the machine ,
2. choose the boot from media,
3. else interuppt the ISL and go for boot hpux -is.
4 Takes it single user mode.
5. modify the /etc/fstab entry.
6. check for the mounting.

If there is any difficulty, try for this link.
http://docs.hp.com/en/B3782-90732/ch02s01.html


Thx,
Analyst.

[TechC]

Thank you much for the reply.
I will try the hpux -is...
Don't know why that did not smack me in the face before. Hopefully the root disk is good, if it is then things will be ok.

Please answer this question for reference.
Can you boot from the Install CD and mount LVM volumes?

Thank you again
James

[Analyst]

>:Can you boot from the Install CD and mount LVM volumes?

The question is not clear.

If I understood your question,

1. boot hpux -is - single usermode
2. boot hpux -lm - LVM maintainace mode.
3. As mentioned earlier boot using singe user mode and do the modification .

Thx,
Analyst.

[TechC]

Sorry for the cloudy question. I guess my question was geared more towards if my usr logical volume was corrupted, could I boot from the install media and mount the /, or /var logical volumes to copy files. I understand hpux -is and hpux -lm but those are relevant only when you have a hard disk that is bootable I believe?

At any rate thank you for your answer, I am just looking ahead to the possibility that the root disk may be failed.
I sure hope that is not the case.

Any idea on if the disk internally in a c360 will work in a c200. Is there a manual that explains the SCSI specifications in regards to the c200 and c360?



Thanks again
James

[Analyst]

James ,

Iam not sure abt that,
may be you can try this link for the comparision.

http://partsurfer.hp.com/cgi-bin/spi/main?sel_flg=modinfo&model=C360&HP_model=

Thx,
Analyst.

[Ramaprasad K]

>>can I pull a disk from c360 and put it in a c200?

You can check the part no. of both the disks and if its similar(sometimes, part nos. might not be same, then check if the 'Replace with HP Part #' matches either), then you should be able to put the disk from c360 to c200.

Regards,
Ramaprasad K

[Matti_Kurkela]

At least on HP-UX 11.00 and above, the install CD has a recovery mode. I'd suspect the same is true with 10.20.

Booting from CD, importing, activating and mounting the vg00 is certainly possible, so you can make changes to fstab.

However, the recovery mode has a *very* limited number of commands by default. Before entering the actual recovery shell, the Install CD's recovery mode offers you a chance to load additional commands from the CD (you choose which commands to load). This is to cope with old machines with a very small amount of RAM.

MK

[TechC]

Matti,
Thank you for the reply. Is there a kb doc that details the steps I may need to perform from recovery mode?

Thank you
James

[Matti_Kurkela]

The ITRC Technical Knowledge Base contains a series of HP-UX Handbooks, formerly known as HP-UX Software Recovery Handbooks.

For this, you'll want Chapter 4, System Recovery. Its Document ID is "emr_na-c01037105". It describes the use of the install CD as a recovery media, its automated recovery procedures and how to use the recovery shell mode.

The Introduction for the series of documents is emr_na-c00863981. Use it to find all the other parts you might be interested in.

You must have a valid support agreement to access the ITRC Knowledge Base.

MK

[TechC]

Matti,
Ouch, that last line about a support agreement was painful. I am gonna have to beg one of my co workers but I appreciate the response. I had accessed that advanced recovery doc in the past when i did have a valid contract, actually I still may.I will have to check it out.

Good news is the box is up now,the root disk was still ok. Pounded out the non lvm entries from single user mode. But we lost a disk and the previous admin did not back the file system up that lived on it.

I will close this thread soon.

Thank you for your help.

James

[TechC]

Hello, issue possibly related.

The lvmtab is not there anymore. How can i recreate this lvmtab file?

Is this a serious issue?

Thank you
James

[TechC]

I see vgscan is used to recreate the lvmtab file. What are the repercussions of running vgscan .man vgscan says only to use it in catastrophic events or if it was deleted.

Not sure why it is missing.


Thanks again
James

[James R. Ferguson · Accepted solution]

Hi James:

> How can i recreate this lvmtab file?

# vgscan -a -v
# vgchange -a y
# lvlnboot -R

Now, if you have any alternate LVM links they may not be in the primary/secondary relationships that they were originally. You can see the order by either doing:

# strings /etc/lvmtab

(or)

# vgdisplay -v

To reorder alternate links to your needs, simply 'vgreduce' a primary link. This promotes the seondary link to primary status. Then 'vgextend' the link you last reduced. THis adds it back to the volume group but as a secondary link. Repeat this for all of your links as necessary.

If you have a large number of pvlinks you can simply 'vgexport' the volume group capturing the device files in a file; edit and reorder the device links; and 'vgimport' the volume group. Thus:

# vgchange -a n /dev/vgNN
# vgexport -m /var/tmp/vgNN.map -f /var/tmp/vgNN.paths /dev/vgNN
# [ ...edit /var/tmp/vgNN.paths ]
# vgimport -m /var/tmp/vgNN.map -f /var/tmp/vgNN.paths /dev/vgNN
# vgchange -a y /dev/vgNN

Regards!

...JRF...

[TTr]

Before 11.x and recovery CDs the HP servers in addition to the installation media they came with the "support media" CD or tape. There was a printed book that came with the media and it described what you could do with it. You booted from the support media just like you would with an install media and get an ISL prompt. From there you could run online and offline diags, STM and boot the support kernel to do system recovery. You would need to find both the media and the book, maybe somebody is selling on ebay.

[TechC]

Thank you Mr. James.

No wonder you are a 2 star Olympian.
I have no pvlinks so I think the set of 3 commands may do the trick.

# vgscan -a -v
# vgchange -a y
# lvlnboot -R

I can do this while in multi user mode then?
I am confused as to why the machine boots up and mounts the lvols if the lvmtab file is off.
I will have to read up on this but is this file unimportant for reasons other than displaying volume group statistics.

Thank you
James
--------------

TTr,
It's a cold world sometimes.

Thank you
James

[TechC]

Thank you all, I am closing this thread. Although I did not get the answer I was looking for I did get some good feed back on the lvm stuff and this was helpful.

James