recover from crash with alt_disk_mksysb

[MoreFeo]

Hi,

I need to recover a p5 550 (AIX 5.3) that crashed. We've talked with IBM and they haven't seen any solution except re-install.

In this server there is a mksysb image on disk (I know it's almost useless to have mksysb on disk, but it's not our server). I think the image is at level 5.3 ML03.

I'm thinking about re-installing, and if the mksysb is still available on disk try to recover it with with alt_disk_install.

I've seen in the infocenter that alt_disk_install is obsolete in AIX 5.3, and that I need to use alt_disk_mksysb.

I wanted to confirm the steps I will need to perform:
- reinstall AIX 5.3 on one disk (hdisk0)
- alt_disk_mksysb -m /path/to/mksysb/image -d hdisk1
- bootlist -m normal hdisk1 hdisk0
- reducevg old_rootvg hdisk0
- extendvg rootvg hdisk0
- mirrorvg onto hdisk0

Should I update the new installation to ML03 before running alt_disk_mksysb?
Is there something I'm missing (more flags on alt_disk_mksysb, etc...)?

Any ideas?

Thanks.

 

[ogniemi]

I would extract /image.data file from mksysb and check if the system was mirrored. if yes, the I would customize the file and use it for "alt_disk_mksysb" command ( check '-i' switch).

After successful alt_disk_mksysb the target drive is automatically set as first on bootlist - anyhow later you can use bootable selecting from SMS memu.

Yes, it will be better you upgrade the interim system to the level you have in mksysb. I guess alt_disk_mksysb could fail if right boot image is not found on the system (not matched with mksysb's level one).

Try it - I see no danger.


kind regards.

 

[ubihga]

Hi

I dont know if I understand you corect.

Your system is crashed, and the mksysb file is ON the crached disk.

If so I would boot in maintenance mode (from CD or via NIM), then I would copy the mksysb file to NIM server then try to restore this mksysb file on the server.


/HGA

 

[MoreFeo]

Well, no NIM, and no other server to configure it as NIM server, it's the only AIX server.

Anyway, we finally re-installed, with preservation, and the mksysb image was on external disks (DS 4300).
We've made mkdvd with this image, ftp it to a windows, recorded it on DVD with record now, and we've been able to boot from it and restore the mksysb.

Thanks anyway.

 

[MoreFeo]

Ogniemi, I have one question.
How can I extract the image.data file from an existing mksysb image, and how can I customize it so it doesn't reinstall mirrored?

Thanks

 

[sbix]

MoreFeo, I am not real sure to have understood, but to me the situation is:
- One system crashed
- On another disk of the same system you have a system image (of a different but quite similar system?) done with MKSYSB.

As ogniemi said you can fetch the image.data file from the system image simply by restoring it.
Infact an mksysb image when on a file, is basically the result of a "backup" command, launched from "/" on all the filesystems belonging to rootvg.
Once you have restored the image file onto the disk where the mksysb image resides, you have to carefully check if this file makes any reference to a mirror disk for rootvg, if so you have to "kill" each of these references and to check if there are any mirrored LV.
If so you will have for each mirrored LV a number of PP (Phisycal Partition) to divide by two.
Once you have done this you can still use the alt_disk_install because it has been superseeded by alt_rootvg_op command in AIX 5.3 but it is still working, because a compatibility version of alt_disk_install which recalls the alt_rootvg_op functions.

Hope to be clear and useful

 

[ogniemi]

Morfeo,

to restore:

# restore -xvf your_mksysb ./image.data
Please mount volume 1 on your_mksysb.
Press the Enter key to continue.

New volume on your_mksysb:
Cluster size is 51200 bytes (100 blocks).
The volume number is 1.
The backup date is: Tue Apr 15 13:03:58 CUT 2008
Files are backed up by name.
The user is root.
x 9655 ./image.data
The total size is 9655 bytes.
The number of restored files is 1.


to be modified in the ./image.data:

in each (rootvg's) filesystem stanzas I change:

COPIES= 2
with
COPIES= 1

PP= N
with
PP= N devided by oroginal copies # or just to be equal LPs=

and (probably nopt necessary but I change it)
LV_SOURCE_DISK_LIST=
so there is only one hdisk on the list.


In that file you can also change other attributes of your VG eg. PP size in the rootvg - but doing it you will have to recalculate all LV's LP and PP numbers.