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VMware Converter Fails on P2V Conversion of RHEL 5.1 Server.

Posted on 2009-07-01
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Last Modified: 2013-12-06
Good Evening,

We are trying to virtualize a small (6GB) RHEL 5.1 web server to a VMware ESX 3i server.  The conversion process fails at 97% after "Creating inital ramdisk (initrd)".  When the new VM boots, it goes into kernel panic since it cannot find the filesystems, such as /dev/root.  We are using the VMware vCenter Converter Standalone 4.0.1 build 161434.

The research has been somewhat challenging saying that:
     1. VMware does not support a "XEN" kernel
     2. You need a VMware Converter Boot CD (which is only available to Enterprise support customers)
     3. You need to manually "fix" the Linux boot config
     4. You need to run a "Linux rescue"
     etc...  

Has anyone successfully converted a RHEL 5.1 server...?  If so, how were you successful?  Thanks in advance for the guidance.
 
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Question by:Bsound
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8 Comments
 
LVL 19

Expert Comment

by:vmwarun - Arun
ID: 24761332
What type of hard disks are you using in the physical Server ? (IDE, SAS, SCSI or SATA)
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Author Comment

by:Bsound
ID: 24762899
The physical server is an HP DL385 with 12GB memory and (3) RAID-5 SAS disks.  Thanks.
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LVL 10

Expert Comment

by:dnilson
ID: 24768016
Its pretty tough to get the free version of the converter to sucessfully convert ANYTHING if its not actually installed on the guest that is being converted, or has direct access to offline VM files themselves.

The non free Enterprise converter indeed does work as advertised from a third computer for P2V on RHEL/ Centos 5.1 installations and may be your best bet if you cant get the free converter to run on the gest Linux box.

This was an issue with 3.5, sorry to hear its not changed in 4.0.  Free vs. paid ....
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Expert Comment

by:dnilson
ID: 24768172
BTW - the XEN kerel is not an issue - XEN is a competing VM platform and its VM file format is somewhat different.  Converters exist between the two but is not relavant from you description above.

Manually fixing th boot config and running a rescue disk amount to the same thing.  The Master Boot Record MBR has 4 entries that can point to physical or extended partions, and the order of partitions in those 4 entries may vary from what was on the original disk.

Since some of the Linux boot cde refreneces the table entries i nthe MBR, if soething else is there, bingo , kernel panic.

Changinging the boot config , or rearranging the MBR to match the physical server are two ways to resolve this.

A bootable .iso imgage of something like PartionMagic, Acronis disk Director, Linux Gparted, or parted magic should anable yo to see both theh old and new MBR to guide you in the fix.

Rescue disks , both the original RHEL, and some of the third party ones o nthe internet (http://www.sysresccd.org/Main_Page ,  http://www.hrlug.org/rescuedisk.html ) should be a big help in troubleshooting / fixing this, if indeed its necessary (the research should have indcated those things MAY be necessary .... ).

If the MBRs are the same, make VERY sure the virtual machine in vcenter was created using the same SCSI adapter thahth te Converter used to do the P2V.
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Accepted Solution

by:
dnilson earned 500 total points
ID: 24810346
I want to take cack something I wrote above in ID:24768172

Its quite relavant if your guest is using a xen kernel, and not the standard el5 kernel.

Without going too deep, the Xen RHEL kernel uses some CPU protected mode instructions in the same protection ring that VMware does - after al lthey are attempting the same feat.  TO allow such a guest to execute that code would crash the host, therefore its not supported.+

Had you booted the machine to a standard el5 kernel, and better yet removed the xen kernel by going into add / REmove program and unselecting the Virtualization option, the conversion should have gone forward normally.

I misread your post earlier thinking that it said a Xen format VM (from the commercial Xen, not the community version) which isnt relavant, but having a running xen kernel at conversion time is.

You might be able to cheat and boot the el kernel , convert, load and execurte, but the system wil likely crash hard.

Is there a particular reason you are running the Xen vs std kernel, and if so, is that reason still valid on a VM version of the server, or did this just happen and can be backed away gracefully in oreder to do the conversion?

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LVL 10

Expert Comment

by:dnilson
ID: 24810356
oh and if you are not sure how to tell, look at the GRUB boot screen, and check the leftmost characters of the image name.

you may want to
yum install yumex
yumex

and select 'instaleld' and search for xen and kernel to make sure its all gone, as there may be several versions on the machine.
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Expert Comment

by:dnilson
ID: 25072656
Hey
Did you ever resolve this issue - or need more help?
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Author Comment

by:Bsound
ID: 25079447
Hi,
My apologies for the delayed response...
The issue has not been resolved.  The server is so old and in need of patching, we decided to build a clean Linux VM and migrate the web application to it.  The server is business-critical, so we didn't want to risk breaking it by making kernel changes.  The new VM build has not yet been scheduled, but we're clear on how to proceed with this approach.
Regardless, thanks a lot for your help and insight.  Your solution was good, but we couldn't afford the service impact if we could not restore the server.
Best Regards,
Bsound.
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