vm.migrate operation failed SR_BACKEND_FAILURE_79

Meth0d

I am trying to move a (rather large) VM from one 8.2 Host to another 8.2 host.
Both are up2date, one needs to run kernel-alt though.

After an hour of copying at around 60MiB the Job fails (the VM has around 6TB in 3 disks):

vm.migrate
{
  "vm": "3db79843-7d43-b13a-2d20-30e2297a700c",
  "mapVifsNetworks": {
    "c89c9bb7-ffba-b8ec-9e5a-d3290102c8eb": "6848e2c6-9ffc-66c8-55c3-a564317a1ae1"
  },
  "migrationNetwork": "6848e2c6-9ffc-66c8-55c3-a564317a1ae1",
  "sr": "85ad8902-0114-6a20-cc80-2f474f25e7c2",
  "targetHost": "a2b237fb-669f-4fbc-803b-33077b723aac"
}
{
  "code": 21,
  "data": {
    "objectId": "3db79843-7d43-b13a-2d20-30e2297a700c",
    "code": "SR_BACKEND_FAILURE_79"
  },
  "message": "operation failed",
  "name": "XoError",
  "stack": "XoError: operation failed
    at operationFailed (/opt/xen-orchestra/packages/xo-common/src/api-errors.js:21:32)
    at file:///opt/xen-orchestra/packages/xo-server/src/api/vm.mjs:482:15
    at Object.migrate (file:///opt/xen-orchestra/packages/xo-server/src/api/vm.mjs:469:3)
    at Api.callApiMethod (file:///opt/xen-orchestra/packages/xo-server/src/xo-mixins/api.mjs:304:20)"
}

I have moved other (smaller) VMs in the same direction between these hosts.

Meth0d

Oh i might have found the issue here

Aug 24 13:13:16 xcp-ng SM: [6430] Raising exception [79, VDI Invalid size [opterr=VDI size must be between 1 MB and 2088960 MB]]

So i cant migrate anything with disks larger 2TB or is there a workaround?

Darkbeldin

@meth0d Unfortunatly i don't think so it's a VDI format limitation see doc here

olivierlambert

We documented that already in https://xcp-ng.org/docs/storage.html#storage-api

Meth0d

@olivierlambert yeah i found that later.
The XO message could be more informative though

olivierlambert

XAPI isn't returning more than just codes that could mean a lot of stuff.

So the problem is more lower on the stack.

Meth0d

Hmm it sounded like SR_BACKEND_FAILURE_79 would only mean one thing as its the same error when you try to create a disk > 2TB. But i know nothing about all that.

"stack": "XapiError: SR_BACKEND_FAILURE_79(, VDI Invalid size [opterr=VDI size must be between 1 MB and 2088960 MB], )

olivierlambert

It's not only this code. But in general, a good way to manage that is: "every message in CAPS is coming from the lower layer" (ie not XO).