[Libguestfs] Communication issues between NBD driver and NBDKit server

[Josef Bacik]

On Sun, May 15, 2022 at 11:45 AM Nikolaus Rath <nikolaus at rath.org> wrote:
>
> Hi,
>
> I am observing some strange errors when using the Kernel's NBD driver with NBDkit.
>
> On the kernel side, I see:
>
> May 15 16:16:11 vostro.rath.org kernel: nbd0: detected capacity change from 0 to 104857600
> May 15 16:16:11 vostro.rath.org kernel: nbd1: detected capacity change from 0 to 104857600
> May 15 16:18:23 vostro.rath.org kernel: block nbd0: Possible stuck request 00000000ae5feee7: control (write at 4836316160,32768B). Runtime 30 seconds
> May 15 16:18:25 vostro.rath.org kernel: block nbd0: Possible stuck request 000000007094eddc: control (write at 5372947456,10240B). Runtime 30 seconds

The server isn't responding to the request fast enough, and you don't
have a timeout set so it'll just hang until you disconnect.

> May 15 16:18:27 vostro.rath.org kernel: block nbd0: Suspicious reply 89 (status 0 flags 0)

The server double replied to a request.  Thanks,

Josef