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    Potential bug with Windows VM backup: "Body Timeout Error"

    Scheduled Pinned Locked Moved Backup
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    • M Offline
      MajorP93 @MajorP93
      last edited by MajorP93

      I did 2 more tests.

      1. using full backup with encryption disabled on the remote (had it enabled before) --> same issue
      2. switching from zstd to gzip --> same issue
      M 1 Reply Last reply Reply Quote 0
      • M Offline
        MajorP93 @MajorP93
        last edited by MajorP93

        Hey, I did some more digging.
        I found some log entries that were written at the moment the backup job threw the "body timeout error". (Those blocks of log entries appear for all VMs that show this problem).

        grep -i "VM.export" xensource.log | grep -i "error"

        Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 HTTPS 192.168.60.30->:::80|[XO] VM export R:edfb08f9b55b|xapi_compression] nice failed to compress: exit code 70
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] [XO] VM export R:edfb08f9b55b failed with exception Server_error(CLIENT_ERROR, [ INTERNAL_ERROR: [ Unix.Unix_error(Unix.EPIPE, "write", "") ] ])
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] Raised Server_error(CLIENT_ERROR, [ INTERNAL_ERROR: [ Unix.Unix_error(Unix.EPIPE, "write", "") ] ])
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 1/16 xapi Raised at file ocaml/xapi/stream_vdi.ml, line 127
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 2/16 xapi Called from file ocaml/xapi/stream_vdi.ml, line 307
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 3/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 24
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 4/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 39
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 5/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 24
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 6/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 39
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 7/16 xapi Called from file ocaml/xapi/stream_vdi.ml, line 263
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 8/16 xapi Called from file list.ml, line 110
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 9/16 xapi Called from file ocaml/xapi/export.ml, line 707
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 10/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 24
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 11/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 39
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 12/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 24
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 13/16 xapi Called from file ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml, line 39
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 14/16 xapi Called from file ocaml/xapi/server_helpers.ml, line 75
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 15/16 xapi Called from file ocaml/xapi/server_helpers.ml, line 97
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace] 16/16 xapi Called from file ocaml/libs/log/debug.ml, line 250
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|VM.export D:6f2ee2bc66b8|backtrace]
Nov  4 08:02:33 dat-xcpng01 xapi: [error||141766 :::80|handler:http/get_export D:b71f8095b88f|backtrace] VM.export D:6f2ee2bc66b8 failed with exception Server_error(CLIENT_ERROR, [ INTERNAL_ERROR: [ Unix.Unix_error(Unix.EPIPE, "write", "") ] ])

        daemon.log shows:

        Nov  4 08:02:31 dat-xcpng01 forkexecd: [error||0 ||forkexecd] 135416 (/bin/nice -n 19 /usr/bin/ionice -c 3 /usr/bin/zstd) exited with code 70

        Maybe this gives some insights 🤔
        To me it appears that the issue is caused by the compression (I had zstd enabled during the backup run).

        Best regards

        //EDIT: This is what ChatGPT thinks about this (I know AI responses have to be taken with a grain of salt):
        Why would there be long “no data” gaps? With full exports, XAPI compresses on the host side. When it encounters very large runs of zeros / sparse/unused regions, compression may yield almost nothing for long stretches. If the stream goes quiet longer than Undici’s bodyTimeout (default ~5 minutes), XO aborts. This explains why it only hits some big VMs and why delta (NBD) backups are fine.

        olivierlambertO 1 Reply Last reply Reply Quote 0
        • olivierlambertO Offline
          olivierlambert Vates 🪐 Co-Founder CEO @MajorP93
          last edited by

          @MajorP93 said in Potential bug with Windows VM backup: "Body Timeout Error":

          Why would there be long “no data” gaps? With full exports, XAPI compresses on the host side. When it encounters very large runs of zeros / sparse/unused regions, compression may yield almost nothing for long stretches. If the stream goes quiet longer than Undici’s bodyTimeout (default ~5 minutes), XO aborts. This explains why it only hits some big VMs and why delta (NBD) backups are fine.

          I think that's exactly the issue in here (if I remember our internal discussion).

          M 1 Reply Last reply Reply Quote 1
          • M Offline
            MajorP93 @olivierlambert
            last edited by

            @olivierlambert said in Potential bug with Windows VM backup: "Body Timeout Error":

            @MajorP93 said in Potential bug with Windows VM backup: "Body Timeout Error":

            Why would there be long “no data” gaps? With full exports, XAPI compresses on the host side. When it encounters very large runs of zeros / sparse/unused regions, compression may yield almost nothing for long stretches. If the stream goes quiet longer than Undici’s bodyTimeout (default ~5 minutes), XO aborts. This explains why it only hits some big VMs and why delta (NBD) backups are fine.

            I think that's exactly the issue in here (if I remember our internal discussion).

            Do you think it could be a good idea to make the timeout configurable via Xen Orchestra?

            1 Reply Last reply Reply Quote 0
            • olivierlambertO Offline
              olivierlambert Vates 🪐 Co-Founder CEO
              last edited by

              I can't answer for my devs, just let them come here to provide an answer 🙂

              G 1 Reply Last reply Reply Quote 1
              • G Offline
                Greg_E @olivierlambert
                last edited by

                @olivierlambert

                Going back up to the top of the thread, removing compression was what fixed this for me, and my backups are still saying they are successful (maybe I better check).

                I wish there was an easier way to "right size" the storage on these Windows VMs, the suggestion is to copy the VM to a new and smaller "disk" but I haven't looked into what is involved to get this done.

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                • olivierlambertO Offline
                  olivierlambert Vates 🪐 Co-Founder CEO
                  last edited by

                  We will fix it with compression, now we are pretty sure to know where the issue is 🙂

                  1 Reply Last reply Reply Quote 0
                  • nikadeN Offline
                    nikade Top contributor
                    last edited by

                    Happy to hear that there's a potential lead, im also happy I found this thread so I can kick back and wait for Vates to fix it 😉

                    1 Reply Last reply Reply Quote 0
                    • M Offline
                      MajorP93
                      last edited by MajorP93

                      I can imagine that a fix could be to send "keepalive" packets in addition to the XCP-ng export-VM-data-stream so that the timeout on XO side does not occur 🤔

                      1 Reply Last reply Reply Quote 1
                      • M Offline
                        MajorP93
                        last edited by

                        I worked around this issue by changing my full backup job to "delta backup" and enabling "force full backup" in the schedule options.

                        Delta backup seems more reliable as of now.

                        Looking forward to a fix as Zstd compression is an appealing feature of the full backup method.

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