freebsd stable - Mar 2017 - moutnroot failing on zpools in Azure after upgrade from 10 to 11 due to lack of waiting for da0

On 16/03/2017 13:18, Pete French wrote:
> 
>> So, the kernel attempted to mount the root even before vmbus was
attached and,
>> thus, before storvsc appeared and informed the kernel that it might be
holding
>> the root.
>> How ZFS was supposed to know that vmbus is ever going to appear?
>> To me this sounds more like a problem with the Hyper-V drivers.
> 
> I am currently running with the patch which waits for a number fo seconds
and
> retries the mount, and that appears t fix it. However I dont really like
rnning
> a patched OS. How would I set about reporting this to Microsoft and getting
it
> fixed, or getting the timeoutpatch commited ? Preferably both, as the
timeout
> patch is generally a useful thing to have working for ZFS I think.
I don't like the delay and retry approach at all.
Imagine that you told the kernel that you want to mount your root from a ZFS
pool which is on a USB driver which you have already thrown out.  Should the
kernel just keep waiting for that pool to appear?

Microsoft provides support for FreeBSD Hyper-V drivers.
Please try to discuss this problem on virtualization@ or with sephe@ directly.


-- 
Andriy Gapon

> I don't like the delay and retry approach at all.
Its not ideal, but it is what we do for UFS after all...
> Imagine that you told the kernel that you want to mount your root from a
ZFS
> pool which is on a USB driver which you have already thrown out.  Should
the
> kernel just keep waiting for that pool to appear?
I'm not talking about an infinite loop here, just making it honour
the 'vfs.mountroot.timeout' setting like it does ofr UFS. So it
should wait for the timeout I have set and then proceed as it would if
there had been no timeout. Default behaviout is for it to behave as it
does now, its onyl when you need the retry that you enable it.

Right now this works for UFS, but not for ZFS, which is an inconsistency
that I dont like, and also means I am being forced down a UFS root
path if I require this.
> Microsoft provides support for FreeBSD Hyper-V drivers.
> Please try to discuss this problem on virtualization@ or with sephe@
directly.
OK, will do, thanks...

-pete.