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    Alert: Control Domain Memory Usage

    Scheduled Pinned Locked Moved Solved Compute
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    • G Offline
      garyabrahams
      last edited by

      Still checking. Going to run for another day and see.

      Should the memory usage in DOM0 be dropping as part of normal use?

      I understand ram usage going up and down just like a normal OS, but a constant increase in memory usage doesn't seem right to me or am I misunderstanding how this work?

      Gary

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

        "Depends". But you shouldn't have invisible RAM used.

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        • F Offline
          fasterfourier @garyabrahams
          last edited by

          @garyabrahams

          Sorry I was unclear, but we are not running Kubernetes in our environment. We are running Citrix Hypervisor 8.2 LTSR.

          F 1 Reply Last reply Reply Quote 1
          • F Offline
            fasterfourier @fasterfourier
            last edited by

            I have another observation to throw in the thread here. In working with Citrix support on our dom0 memory exhaustion issue in CH8.2LTSR, they are focusing on several of our VMs that had dynamic memory control enabled, which is deprecated in CH8.x. They believe this is related to the control domain memory exhaustion.

            I have disabled this on all VMs that I can find with the feature enabled and will continue to monitor. I don't have much hope that this is the underlying issue, since we are seeing the memory issue on our pool master, which could only have hosted a VM with DMA enabled for very brief periods of time while other VMs were shuffled around for maintenance.

            Does this track with anyone else here?

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            • stormiS Offline
              stormi Vates 🪐 XCP-ng Team
              last edited by stormi

              This is... Surprising. I thought xl top would allow to rule that out very fast (and it did earlier in this thread when I suspected something related to dom0 memory ballooning). Unless Xen leaks the memory in some way that would not be visible to itself. I don't know if that is even possible and I don't see how that would relate at all with the memory used by dom0, even if there was such a leak related to domU DMC.

              F 1 Reply Last reply Reply Quote 0
              • F Offline
                fasterfourier @stormi
                last edited by

                @stormi

                I am also suspicious of this diagnosis, and I think this is likely related to checking off the "misalignments" in our configuration before escalating the case to the next level of troubleshooting support. That said, I figured I'd run it by the group here to see if there's any correlation between users with dynamic memory on their VMs and this issue.

                F 1 Reply Last reply Reply Quote 1
                • G Offline
                  garyabrahams
                  last edited by

                  The boxes that I have do not have dynamic memory (never used it), and we are getting the issue.

                  Some feedback on my test box running 8.0 alternative kernel. Been running it for a week and getting this.

                  04be28e3-1c89-4e8b-8c02-754a3909759a-image.png

                  As you can see there was a increase in memory of the first few days, but then it seemed to level off. I'll continue to do some tests, then I'm intending to upgrade to 8.2 and see if I can replicate (both with the standard and alternative kernels).

                  I'll provide feedback once I have it.

                  Gary

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                  • G Offline
                    garyabrahams
                    last edited by

                    I have another production box that has this issue.. and noticed this

                    [10:41 host ~]# free -m
                                  total        used        free      shared  buff/cache   available
                    Mem:           7913        6445          77         210        1390         284
                    Swap:          1023          41         982
                    
                    [10:41 host ~]# ps -ef | grep sadc | wc -l
                    6337
                    
                    [10:41 host ~]# ps -ef | grep CROND | wc -l
                    6337
                    
                    [10:41 host ~]# ps -ef | grep 32766
                    root       306 32766  0 Jan31 ?        00:00:00 /usr/lib64/sa/sadc -F -L -S DISK 1 1 -
                    root     32766  2898  0 Jan31 ?        00:00:00 /usr/sbin/CROND -n
                    

                    Not sure why I have 6337 processes for CROND and sadc, but going to do some investigations

                    stormiS 1 Reply Last reply Reply Quote 0
                    • daveD Offline
                      dave
                      last edited by

                      [10:36 xs03 ~]# free -m
                                    total        used        free      shared  buff/cache   available
                      Mem:          11921       11322         171         151         427         175
                      Swap:          1023          37         986
                      [10:36 xs03 ~]# ps -ef | grep CROND | wc -l
                      1
                      
                      

                      BTW: All my affected pools never had dynamic memory.

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                      • stormiS Offline
                        stormi Vates 🪐 XCP-ng Team @garyabrahams
                        last edited by stormi

                        @garyabrahams I think this is a separate issue that would deserve a separate thread, though it's interesting to have mentioned it here just in case someone else would have noticed something similar (I don't remember anyone mentioning such proliferation of processes in this thread).

                        Now, maybe that host also is affected by the memory leak, but for now nothing allows to think both issues are related. Or maybe the lack of free memory is what caused the processes to never quit.

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                        • F Offline
                          fasterfourier @fasterfourier
                          last edited by

                          Update: we have disabled dynamic memory on all VMs in our pool and the issue is still occurring.I expect this to be sent to the citrix developers shortly, since the normal support team has exhausted their troubleshooting options.

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                          • G Offline
                            garyabrahams
                            last edited by

                            An update from my side.
                            I have tried 8.0 alt kernel, 8.2 standard kernel and 8.2 alt kernel and in each case the memory usage increased over time

                            Below the first increase is 8.0 alt kernel, 2nd increase was 8.2 standard and 3rd 8.2 alt kernel.

                            f93cf91b-910b-47b8-a1d4-0883b7f9a20a-image.png

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

                              I don't think there's enough time to really be sure about the memory leak. It's normal to see raising RAM usage, what's not is to consume all the dom0. Can you wait a bit longer between 2 tests?

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                              • O Offline
                                OlivierD
                                last edited by

                                Hello,
                                I can confirm we encountered this issue on several hosts in the past few months.

                                Config :

                                • Server is Dell PowerEdge M630
                                • local storage on SSD + remote SR on ISCSI
                                • kernel used: kernel-4.19.19-6.0.11.1.xcpng8.1.x86_64
                                • we use ixgbe (intel-ixgbe-5.5.2-2.xcpng8.1.x86_64) and network cards are Intel 82599 10 Gigabit dual Port (with bonding on XCP NG).
                                • firmwares up to date (less than 6 months, when we updated to XCP-NG 8.1+).

                                Additional informations :

                                • we don't have any VM with memory ballooning
                                • shutting down VMs does not free memory
                                • we don't do many operations each day (less than 5 reboots/stop/start).
                                • size of pools does not matter (bug happened with two hosts and on another pool with 10 hosts).

                                According to some messages, it seems kernel-alt fixes the issue ... We'll try to switch kernel when we encounter the issue again.

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

                                  Yes, please, keep us posted 🙂

                                  Thank for your feedback!

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                                  • F Offline
                                    fasterfourier
                                    last edited by

                                    One more observation here. This issue does not occur on a different pool of ours that's also running CH8.2LTSR. That pool has lower loading overall, 2 hosts instead of 7, and does not contain any NICs using the ixgbe driver. Other aspects of the pool are identical.

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                                    • stormiS Offline
                                      stormi Vates 🪐 XCP-ng Team @stormi
                                      last edited by

                                      @stormi said in Alert: Control Domain Memory Usage:

                                      Before I realized that not every affected host was using the ixgbe driver, contrarily to what I initially thought, I built an alternate driver from the latest sources from Intel.

                                      So, even if there's little hope that it will fix anything, here's how to install it (on XCP-ng 8.1 or 8.2):

                                      yum install intel-ixgbe-alt --enablerepo=xcp-ng-testing
                                      reboot
                                      

                                      Has anyone tested the updated ixgbe driver?

                                      daveD 1 Reply Last reply Reply Quote 2
                                      • daveD Offline
                                        dave @stormi
                                        last edited by

                                        @stormi

                                        I upgraded a pool which was affected from 8.1 to 8.2 this weekend and installed the driver on one of the Hosts. Its a little early, but as you can see, there seems to be a difference in the memory usage:

                                        Stock Driver

                                        c53f2add-8bbe-4203-bba8-97e94b466c56-image.png

                                        Stromis Driver:

                                        57bf6a63-eff5-47ca-a155-b918c12b95b2-image.png

                                        One can allready see a constanty, slowly growing mem-usage in "small steps" on the Server with the stock driver, wheras the server with stormis driver seems to be stable.

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

                                          Indeed, sounds better in any case! Thanks a lot @dave for the feedback.

                                          For everyone else with the issue: please try the same and report. Maybe we found the culprit!

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

                                            That's really likely the problem all along.

                                            See https://sourceforge.net/p/e1000/bugs/633/#af80/154d

                                            So our alt driver is indeed fixing it 🙂

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