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    Testing ZFS with XCP-ng

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

      @stormi this is for you 🙂

      1 Reply Last reply Reply Quote 0
      • stormiS Offline
        stormi Vates 🪐 XCP-ng Team
        last edited by

        I knew we shouldn't have released on a Friday just before my holidays 🙂

        XCP-ng community, note that I do that for you!

        To answer the question, the zfs-tests package is not strictly needed so let's not install it (it pulls too many dependencies that we would have to add. We can consider making it installable later.). We forgot to add some steps in the procedure. We have updated it now.

        If you run:
        depmod -a

        Then you should be able to run
        modprobe zfs

        This should bring you at least a step further.

        1 Reply Last reply Reply Quote 2
        • borzelB Offline
          borzel XCP-ng Center Team
          last edited by

          @eexodus If it's not working, we can chat to troubleshoot your issue 📰

          stormiS 1 Reply Last reply Reply Quote 0
          • stormiS Offline
            stormi Vates 🪐 XCP-ng Team @borzel
            last edited by

            @borzel It would be nice also to improve https://github.com/xcp-ng/xcp/wiki/ZFS-on-XCP-ng-7.5-and-later because I wrote it and I never used zfs!

            borzelB 1 Reply Last reply Reply Quote 0
            • E Offline
              eexodus
              last edited by eexodus

              @stormi @borzel Thank you. I was able to create the zpool with those two extra commands. I then created a dataset and created a type=file and device-config:location SR. I realize ZFS is still a new feature, but is that the recommended way? I'm completely new to Xen so I am not familiar with creating SRs.

              [root@xcp-ng-miqfcsgc] depmod -a
              [root@xcp-ng-miqfcsgc] modprobe zfs
              [root@xcp-ng-miqfcsgc] zpool create -f tank /dev/sda
              [root@xcp-ng-miqfcsgc] zfs create tank/sr
              [root@xcp-ng-miqfcsgc] xe sr-create host-uuid=MY_UUID name-label=zfs-sr type=file other-config:o_direct=false device-config:location=/tank/sr/zfs-sr
              
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              • borzelB Offline
                borzel XCP-ng Center Team
                last edited by

                @eexodus said in Testing ZFS with XCP-ng:

                zpool create -f tank /dev/sda

                If you have 4k disks (aka Advanced Format) use ashift=12

                zpool create -o ashift=12 -f tank /dev/sda
                

                I would say, for the first testing, please use:

                zfs set sync=disabled tank
                zfs set compress=lz4 tank
                zfs set atime=off tank
                

                pool/discs can be live monitored with

                zpool iostat -v 1
                
                A 1 Reply Last reply Reply Quote 3
                • A Offline
                  AllooTikeeChaat @borzel
                  last edited by

                  @borzel Not sure if this thread is the right place to ask .. but whats the min and recommended requirements to test ZFS ?

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

                    Well, depends on the level of perfs you want to achieve. A lot of RAM is the key.

                    borzelB 1 Reply Last reply Reply Quote 0
                    • borzelB Offline
                      borzel XCP-ng Center Team @olivierlambert
                      last edited by

                      @olivierlambert said in Testing ZFS with XCP-ng:

                      A lot of RAM is the key.

                      And if you want more performance, add more RAM 🙂

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                      • borzelB Offline
                        borzel XCP-ng Center Team @stormi
                        last edited by

                        @stormi said in Testing ZFS with XCP-ng:

                        @borzel It would be nice also to improve https://github.com/xcp-ng/xcp/wiki/ZFS-on-XCP-ng-7.5-and-later because I wrote it and I never used zfs!

                        I have no write permissions 😐

                        stormiS 1 Reply Last reply Reply Quote 0
                        • borzelB Offline
                          borzel XCP-ng Center Team
                          last edited by borzel

                          Good ressource with a lot of information, how to really use ZFS, build storages, tuning, etc.: https://www.zfsbuild.com 📰

                          B 1 Reply Last reply Reply Quote 0
                          • B Offline
                            buzzzo @borzel
                            last edited by

                            Zfs is a local sr and imho does not add too much advantages vs classic ext sr

                            The real value of zfs is to use built in replication to remote zfs system.
                            Proxmox has built a very interesting solutions around it: async replication of vm on a another node.

                            I know xoa already offer a similar solution but is snapshot based and everyone knows the performance and size problem with this approach.

                            borzelB olivierlambertO 2 Replies Last reply Reply Quote 0
                            • borzelB Offline
                              borzel XCP-ng Center Team @buzzzo
                              last edited by borzel

                              @buzzzo said in Testing ZFS with XCP-ng:

                              Zfs is a local sr and imho does not add too much advantages vs classic ext sr

                              meeeep 🙂

                              • ZFS uses (in standard configuration) half the RAM as read cache
                              • with sync=disabled your writes are faster (but synced to discs every 5 seconds; in one sequential batch - efficient use of slow spinning drives!)
                              • it has checksums from fs-layer down to the device
                              • it's awesome 😉

                              know xoa already offer a similar solution but is snapshot based and everyone knows the performance and size problem with this approach.

                              If we all had 48 hours a day and more people in the team, we could fully integrate ZFS into XCP-ng (with all bells and whistles). But for now we are happy to have the first step done - loose integrate ZFS to start using it and testing stability of the dom0 with ZFS in it.

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

                                @buzzzo Double meeeep 😆

                                On file level SR (ext, NFS, local ZFS, XOSAN), there is no space issue doing snapshots. Also, perfs are good even with snapshots if you don't have an asthmatic SR.

                                B 1 Reply Last reply Reply Quote 0
                                • B Offline
                                  buzzzo @olivierlambert
                                  last edited by

                                  @olivierlambert meeep!!! ☺

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

                                    Meep meep!

                                    1 Reply Last reply Reply Quote 1
                                    • borzelB Offline
                                      borzel XCP-ng Center Team
                                      last edited by borzel

                                      I tested latest and greatest XO (5.24.1 from sources) with latest XCP-ng 7.5 (incl. xcp-ng-extra repo/ZFS). Backups do not work 😞

                                      If the VDI is on a ext-SR, all is fine, backup working.
                                      If the VDI is on a File-SR (ZFS based), the backup says "VDI_ERROR" or "VDI Chain to long". I will provide logfiles tomorrow if needed.

                                      Setup of my File-SR:
                                      xe sr-create host-uuid=<xxx> name-label=zfssr type=file other-config:o_direct=false device-config:location=/zfspool/zfssr

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

                                        VDI chain too long doesn't seems related. It means you have a VDI chain that's around 30 files.

                                        Can you provide the exact/detailed error log?

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                                        • borzelB Offline
                                          borzel XCP-ng Center Team
                                          last edited by borzel

                                          0_1534286419566_560b7fad-965d-42bc-8f40-2eed276163b8-grafik.png

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                                          • borzelB Offline
                                            borzel XCP-ng Center Team
                                            last edited by borzel

                                            I searched in xensource.log, SMlog and syslog, no related entries found 😞

                                            How can I increase the loglevel of XO?

                                            Here's the log output if I start this job again:

                                            Aug 15 01:10:35 ubuntu xo-server[616]: 2018-08-14T23:10:35.241Z xo:xapi Snapshotting VM pmg as [XO Backup test] pmg
                                            Aug 15 01:10:36 ubuntu xo-server[616]: 2018-08-14T23:10:36.948Z xo:xapi exporting VDI pmg 0
                                            Aug 15 01:10:41 ubuntu xo-server[616]: 2018-08-14T23:10:41.289Z xo:xapi Deleting VM [XO Backup test] pmg
                                            Aug 15 01:10:41 ubuntu xo-server[616]: 2018-08-14T23:10:41.585Z xo:xapi Deleting VDI pmg 0
                                            

                                            It's nearly nothing...

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