XOSTOR appears to be broken on the new XCP-NG May 2026 update

[ccooke]

After the update, the master server (first to be updated, of course) can no longer attach the xostor SR.
I have verified that the rolling pool update did look for updated packages, and that xostor is still installed and working (thankfully the linstor services are working fine, so there's no risk of data loss here).

When trying to mount the SR, the master host gets this error:

[19:02 goethite ~]# xe pbd-plug uuid=91e19949-cf2c-b1bb-7dda-d2c114c113a1 
Error code: SR_BACKEND_FAILURE_46
Error parameters: , The VDI is not available [opterr=Could not load 5cb360ea-0904-472c-a3f9-1a44b97936c3 because: ['UNKNOWN_XENAPI_PLUGIN_FUNCTION', 'getInfo'] (openers: {'hematite.earth.gkhs.net': {'26922': {'process-name': '+tapdisk', 'open-duration': '612038496'}}, 'goethite.earth.gkhs.net': {}, 'siderite.earth.gkhs.net': {}})], 

I would advise nobody updates a host using XOSTOR until this gets fixed!

[dthenot]

@ccooke Hello,

You should be able to make the XOSTOR SR work again if you update sm and sm-fairlock on the other hosts.

yum update sm sm-fairlock

Then you should be able to re-plug the SR on the master and proceed with the RPU.

[ccooke]

@dthenot ... The XOSTOR SR is working on the other hosts. It's only the master which updated where it fails to plug the pbd. Given that it can't mount the pbd after doing the update, I am very doubtful about updating another host.
What's more, I can't without shutting down a large number of VMs or doing a long migration off the XOSTOR, because I only have N+1 redundancy on my personal cluster, and we're already one host down because the master can't rejoin the XOSTOR SR.

In short, this looks like a very dangerous suggestion - sorry!