Update:
It’s weird:
• There are three VM’s on this host. The backup works with two but not with the third. It does with the “Body Timeout Error” error.
• Two of the VM’s are almost identical (same drive sizes). The only difference is that one was set up as “Other install media” (came over from esxi) and the one that fails was set up using the “Windows Server 2022” template.
• I normally backup to multiple NFS servers so I changed to try one at a time; both failed.
• After watching it do the backup too many times to thing, I found that, at about the 95% stage, the snapshot stops writing to the NFS share.
• About that time, the file /var/log/xensource.log records this information:
o Feb 26 09:43:33 HOST1 xapi: [error||19977 HTTPS 192.168.1.5->:::80|[XO] VM export R:c14f4c4c1c4c|xapi_compression] nice failed to compress: exit code 70
o Feb 26 09:43:33 HOST1 xapi: [ warn||19977 HTTPS 192.168.1.5->:::80|[XO] VM export R:c14f4c4c1c4c|pervasiveext] finally: Error while running cleanup after failure of main function: Failure("nice failed to compress: exit code 70")
o Feb 26 09:43:33 HOST1 xapi: [debug||922 |xapi events D:d21ea5c4dd9a|xenops] Event on VM fbcbd709-a9d9-4cc7-80de-90185a74eba4; resident_here = true
o Feb 26 09:43:33 HOST1 xapi: [debug||922 |xapi events D:d21ea5c4dd9a|dummytaskhelper] task timeboxed_rpc D:a08ebc674b6d created by task D:d21ea5c4dd9a
o Feb 26 09:43:33 HOST1 xapi: [debug||922 |timeboxed_rpc D:a08ebc674b6d|xmlrpc_client] stunnel pid: 339060 (cached) connected to 192.168.1.6:443
o Feb 26 09:43:33 HOST1 xapi: [debug||19977 HTTPS 192.168.1.5->:::80|[XO] VM export R:c14f4c4c1c4c|xmlrpc_client] stunnel pid: 296483 (cached) connected to 192.168.1.6:443
o Feb 26 09:43:33 HOST1 xapi: [error||19977 :::80|VM.export D:c62fe7a2b4f2|backtrace] [XO] VM export R:c14f4c4c1c4c failed with exception Server_error(CLIENT_ERROR, [ INTERNAL_ERROR: [ Unix.Unix_error(Unix.EPIPE, "write", "") ] ])
o Feb 26 09:43:33 HOST1 xapi: [error||19977 :::80|VM.export D:c62fe7a2b4f2|backtrace] Raised Server_error(CLIENT_ERROR, [ INTERNAL_ERROR: [ Unix.Unix_error(Unix.EPIPE, "write", "") ] ])
• I have no idea if it means anything but the “failed to compress” made me try something. I change “compression” from “Zstd” to “disabled” and that time it worked.
Here are my results:
Regular backup to TrueNas, “compression” set to “Zstd”: backup fails.
Regular backup to TrueNas, “compression” set to “disabled”: backup is successful.
Regular backup to vanilla Ubuntu test VM, “compression” set to “Zstd”: backup is successful.
Delta backup to TrueNas: backup is successful.
Sooooo…the $64,000 question is why doesn’t it work on that one VM when compression is on and it a TrueNas box?