How VMware vCenter Converter Standalone actually works?

[selena1]

Hi, I have one question just to be sure.
I need to know how VMware vCenter Converter Standalone actually works.

We are migrating some windows and linux machines with VMware vCenter Converter Standalone 4.0.1 build-161434. We are doing hot cloning. I have found in datasheet that VMware vCenter Converter is using sector-based copying. VMware vCenter Converter first takes a snapshot of the source machine before migrating the data. This way there isn't any downtime of source server.

We are cloning machines and after cloning has finished we are shuting down old machines.

My question is.

We are starting cloning of machine server1 at 8:00 PM. VMware vCenter Converter make a snapshot. Users are still working on this machine and making some changes. Machine cloning has finished at 10:00 PM. We are shuting down old machine (server1) and new cloned machine takes all their functions.

So, what is happening with changes that users made from 8:00 PM (when snapshot has been created) till 10:00 PM when new cloned machines start to be functional. Are all the changes created after snapshot has been created have been applied to cloned machine?


Thanks in advance.

 

[baddos]

I've used this tool before and it's worked out well for me, but when I did it nobody was using the system so i don't know how it would handle files that have changed.

 

[Roadki11]

I would use the converter boot disc and do cold conversions. Less issues, especially if you are converting DC's or DB servers. I have done warm conversions and had very little issues but I also did them with no one else on the systems. Just remember to bring up the converted machines with the network not connected the first time. You lose your nic settings because it sees a new adaptor, this is true with warm or cold conversions.

RoadKi11

"This apparent fear reaction is typical, rather than try to solve technical problems technically, policy solutions are often chosen." - Fred Cohen

 

[selena1]

Thanks for your replies.

I've checked and tested this and looks like VMware is not telling complete truth here about hot migration. This is maybe true for forms or web servers where users don't change anything on server. For other servers users should be restricted from accessing server during migration. In this case server is not available to users so I can turn it off and make cold migration. It is the same.

I've chacked hot migration on one server. After migration start at 8:00 PM I've created new example.txt file on C partition. This file haven't been migrated. Only files from the time of snapshot at 8:00 PM.

http://searchvmware.techtarget.com/tip/0,289483,sid179_gci1304471,00.html

Hot and cold cloning
There are two methods used to clone a server, hot cloning (while the server OS is running) or cold cloning (from a boot CD (Windows PE) while the server's OS is not running). Which method you choose will depend on the type of server you are converting. Cold cloning offers the best chance of success because the server OS is not running which will ensure that no data is corrupted since there are no open files while the conversion process is running. This is the best option for data sensitive servers like database and email servers.

Hot cloning works well for less sensitive servers that have more static content like web, print, DNS and application servers. Hot cloning works by creating a snapshot at the beginning of the cloning process and then copying that snapshot to the newly create VM. Any files that are open at the time of the snapshot may not have their data committed which will result in a crash-consistent state for your destination VM. Any subsequent changes to any files after the snapshot is taken will not be copied as well. The snapshot basically creates a point-in-time reference and tracks any block-level changes to the files in the file system. The cloning process uses the snapshot and the files to assemble a reasonable picture of what the entire disk looked like.

Cheers....

 

[SimonDavies]

I fail to see what your problem with Hot Migration is? How do you think it will do the conversion if files are constantly changing, it can't re-convert the file everytime it changes because then there could be a chance that the P2V never actually finishes.

As a rule I would always go for a cold migration, however I have seen hot migrations succeed just as much as cold migrations.

Simon

The real world is not about exam scores, it's about ability.

 

[ArizonaGeek]

I am in agreement with Simon, cold migration to "changing" servers or hot migration for others.

A few things I've found, it is WAY easier to create a new server and migrate settings for things like SQL and domain controllers (in fact doing a P2V on a DC would cause you all kinds of heartache) than doing a P2V.

One of the users in our local VMUG created a P2V checklist to help out in doing one. You may have to log in with your VMWare login to get to that doc.

Don't forget to remove the old hardware from device manager in the new virtual server.

Cheers
Rob

The answer is always "PEBKAC!