Comment 8 for bug 1779815

I'm investigating an issue we're seeing on a couple ARM servers, and it looks like this maybe the same issue here. What it looks like is that the mpt3sas driver is being downloaded/loaded just before the partitioner starts. Since the kernel is configured to scan for SCSI devices asynchronously, the partitioner ends up being displayed before disk detection has completed. When the reporter goes "Back" and re-enters the partitioner, the disks now appear because scanning has completed in the meantime.

The proposal in comment #3 would pre-load the mpt3sas driver into the initrd instead of fetching it from the mirror. This would make it available earlier in the installer which, for this case, may give mpt3sas enough time to complete its asynchronous scan before getting to the partitioner phase. But, I don't think it fixes the general problem. I suspect systems with lots of disks and/or automated (preseeded) installs would still be at risk of running into this race.

Back-in-the-day, there was a scsi_wait_scan module that you could load, and insmod would block until all asynchronous scans were complete. That no longer exists, and I haven't been able to find a reasonable userspace replacement. One thing we *could* do is add scsi_mod.scan=sync to d-i before the "---", which would force synchronous scanning during install time, but leave asynchronous scanning enabled for the runtime.