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    XenServer Export Performance Seems Poor

    IT Discussion
    xenserver xenserver 6.5 gzip
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    • BRRABillB
      BRRABill
      last edited by

      After some research today, I have come to the conclusion (could be wrong) that EXPORT does not compress. I came to this conclusion because a lot of the articles I saw spoke of compressing the export.

      But it seems like it was said in the thread it IS enabled.

      So confusing...

      Take a look at this:
      https://www.citrix.com/blogs/2009/02/10/xenserver-tips-and-tricks-minimize-the-size-of-your-exported-virtual-machines/

      "In the interest of not overloading the system that is exporting the virtual machine we don’t compress the data that is exported. So to really save on space after you do an export you can then use your favorite compression program to shrink down the exported file even more. "

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      • BRRABillB
        BRRABill
        last edited by

        I also found today the copy through XO is really slow. I wonder why...

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        • DashrenderD
          Dashrender
          last edited by

          XO might be doing the compression, and XC might not be doing compression.

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          • BRRABillB
            BRRABill
            last edited by

            Next week I am going to test everything.

            All I know if=s last night when I gave up copying through XO, I was getting out 4-8MBps. A straight export today got me in the 50-60MBps range. Not super fast, but a hell of a lot better. It did 12 GB in around 5 minutes.

            I think copy is slow for some reason, but I've looked through so much XS/XO stuff today I can't think anymore.

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            • olivierO
              olivier
              last edited by

              XO is activating the compression by default for a VM copy. And because of GZIP and probably a not so fast CPU, the bottleneck is there.

              Sadly, we had a choice to make, between faster copy but larger bandwidth usage and the opposite. Changing it is easy, but I have a bad feeling about this (a lot of people not agree with the new choice).

              The best would be to have the choice, but it's tricky in term of UI.

              DashrenderD 1 Reply Last reply Reply Quote 0
              • DashrenderD
                Dashrender @olivier
                last edited by

                @olivier said in XenServer Export Performance Seems Poor:

                XO is activating the compression by default for a VM copy. And because of GZIP and probably a not so fast CPU, the bottleneck is there.

                Sadly, we had a choice to make, between faster copy but larger bandwidth usage and the opposite. Changing it is easy, but I have a bad feeling about this (a lot of people not agree with the new choice).

                The best would be to have the choice, but it's tricky in term of UI.

                Didn't there used to be a check box to enable or disable GZIP?

                olivierO 1 Reply Last reply Reply Quote 0
                • olivierO
                  olivier @Dashrender
                  last edited by

                  @Dashrender For backup yes, not for VM copy.

                  BRRABillB 1 Reply Last reply Reply Quote 0
                  • BRRABillB
                    BRRABill @olivier
                    last edited by

                    @olivier

                    Is there a way to export without compression directly from XS, and bypass XC and XO?

                    It's not something that happens a lot, but boy those slow speeds are a killer. It adds many hours to a job you;d like to happen as quick as possible.

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                    • BRRABillB
                      BRRABill
                      last edited by

                      Also...

                      When I did my test export, I was seeing around 5--60 MBps. Not super fast considering it is GB, but not terrible.

                      When I did the actual export of my shutdown VM, it slowed down to 20MSps or less. Same setup (aka where the export was going).

                      Is this because of compression?

                      I also realized it must read every block in the provisioned disk, because it got to a certain point pretty quickly (90GB) and then just sat and sat for over an hour. (The disk is provisioned at 200GB.)

                      Seems like there are still a lof of unanswered questions here.

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                      • olivierO
                        olivier
                        last edited by

                        You can create a basic backup schedule and de-activate the compression, then run the job manually. You'll have an export without compression.

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                        • BRRABillB
                          BRRABill @olivier
                          last edited by BRRABill

                          @olivier said in XenServer Export Performance Seems Poor:

                          You can create a basic backup schedule and de-activate the compression, then run the job manually. You'll have an export without compression.

                          When I was running my test, it seemed the exporting directly from XC was quicker than running a one time backup from XO of the same VM to the same location. The export of a small VM (I set it up just for testing this) was about 6 minutes, and the backup was 13.

                          But it sounds like what you are saying is that it should have been the opposite.

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