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    Cold versus Hot

    continuum Guru
    User ModeratorsCommunity Warriors

      In my experience with P2V - doing it myself and watching the forums - I notice that most experienced P2V admins prefer Cold-clones while newbies prefer Hotclones.

       

      It also looks like VMware only recommends hotclones ...

       

      Just curious - what is your prefered way ?

        • 1. Re: Cold versus Hot
          nsolop Expert

          Whenever is possible I prefer  coldclones... if there is no other option hotclones

          • 2. Re: Cold versus Hot
            continuum Guru
            User ModeratorsCommunity Warriors

            what do you mean by "if there is no other option ..."

             

            stuborn users or driver-issues or "no downtime allowed" ?

            • 3. Re: Cold versus Hot
              nsolop Expert

              In some cases I had to perform a p2v of a remote server that didn't have an ILO or DRAC or even a working CD drive and the only way to do the p2v was hotclone.

               

              Sorry about my english :S

              • 4. Re: Cold versus Hot
                continuum Guru
                Community WarriorsUser Moderators

                would you be able to coldclone such cases if you had a bootable USB-stick ?

                 

                hmm - I guess not

                • 5. Re: Cold versus Hot
                  nsolop Expert

                  Nope, old servers/desktops without USB boot option

                  • 6. Re: Cold versus Hot
                    wtfmatt Novice

                    I'm a relatively new VMware admin, and I run a very small shop.  (4 hosts, 25 guests)

                     

                    I've performed 12 P2V's

                     

                    - 1 Server 2000

                    - 4  Server 2003

                    - 7  Server 2008R2

                     

                    I've done them all hot, with no issue.  Are there specific reasons most admins prefer coldcloning?

                    • 7. Re: Cold versus Hot
                      bulletprooffool Virtuoso
                      User Moderators

                      I stop as many services as possible and the hot clone.(most of the time)

                      Stopping all the services prevents changes on the machine and running it with the OS running gets me around any access issues to disks that are SAN attached / on unsupported controllers etc. - also means I can maintain RDP access in case anything goes wrong.

                      • 8. Re: Cold versus Hot
                        Josh26 Master

                        Nicolas Solop wrote:

                         

                        In some cases I had to perform a p2v of a remote server that didn't have an ILO or DRAC or even a working CD drive and the only way to do the p2v was hotclone.

                         

                        Sorry about my english :S

                        Nearly every p2v I have done has been like this - and I'm not going to drive to a DC to plugin a USB key if I can help it.

                         

                        All mine have been hot, and I stop every service I can first.

                        • 9. Re: Cold versus Hot
                          ivivanov Expert
                          VMware Employees

                          When performing Windows P2V Converter has the option for a "synchronization", that means a second pass copying the changes that occurred during the initial "long" cloning process. Also you can select list of services to stop on the source automatically just before the synchronization process starts. This allows minimizing the downtime of the source. And in 5.0 release there is also an option for "enhanced synchronization", allowing to run multiple incremental updates and actually schedule them for appropriate time.

                          • 10. Re: Cold versus Hot
                            eeg3 Master

                            While I prefer cold clone, it seems VMware is killing that option as newer releases. Is there a reasoning behind that?

                            • 11. Re: Cold versus Hot
                              ivivanov Expert
                              VMware Employees

                              Well, I guess everyone has different preferences :-).

                               

                              Here are some features of hot cloning that support the motivation for preferring hot cloning over cold cloning:

                               

                              * Run the agent on the source - no need to deal with source hardware (network and disks), but use the source OS to do this instead.

                              * Minimize downtime of the source (it is up and running while the conversion proceeds)

                              * Track changes during initial cloning and synchronize them during a second pass (minimize data loss)

                              * Allow stopping services before synchronization (guarantee critical services won't generate changes that won't be transferred).

                              * (introduced in 5.0) Allow multiple incremental synchronizations - you can keep a VM "copy" of the source up-to-date and switch to it at any time.

                               

                              The only "pro" I can think of cold clone is it allows you get a consistent source image. It is important, but you get the same result with hot-cloning (of Windows sources) because of incremental synchronization, stopping services on source and creating VSS snapshot and transfer data from it instead of the raw disk. For Linux sources there is no snapshotting, however currently there is no way to perform automated cold-clone of Linux sources anyway.

                               

                              Besides you can always use some third-party backup software, create a backup image of the source machine and then convert this image to a VMware VM (Converter supports multiple backup image formats).

                               

                              What is you reasoning for preferring cold cloning?.

                              • 12. Re: Cold versus Hot
                                eeg3 Master

                                Just personal experience/preference, I suppose. Things seem to go smoother via cold clone (when it works). If I'm disabling services, it's almost the same as downtime, anyhow.

                                 

                                A lot of the features in 5.0 are very cool, though.

                                • 13. Re: Cold versus Hot
                                  jcwuerfl Hot Shot

                                  COLD !  -  As you know that NOBODY! will be doing anything on the server, there will be nothing open and get a "cleaner" clone.

                                  • 14. Re: Cold versus Hot
                                    ivivanov Expert
                                    VMware Employees

                                    Yep, and a few hours downtime. With hot clone you get virtually the same level of consistency when using synchronization and stop the services on the source only during the synchronization step (which usually takes a few minutes). Well, if a user has opened a MS Word document on the source machine and is typing as the conversion proceeds, most likely s/he will lose some data if not saved before the synchronization step started :-).

                                     

                                    As I said earlier, if you really insist on cold-cloning you can do it using a third-party backup software, take an offline image and then convert the image to a VM using Converter. It would require more free disk space though as well as a backup software, however it is doable, but there is no easy way to do the same for hot-cloning, so I guess this is why we have put more efforts in hot-cloning...

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