Date: Tue, 8 Feb 2022 06:38:51 +0000 From: Graham Perrin <grahamperrin@gmail.com> To: freebsd-current <freebsd-current@freebsd.org> Subject: FreeBSD guests behaving as if their boot disks have disappeared (was: USB Disk Stalls on -current) Message-ID: <edd5608e-dfd3-ba02-463d-45f04d333168@gmail.com> In-Reply-To: <CANCZdfqG-%2B9dfFz-%2BeezZaqbPQN5-mQpw%2B214CkiKC%2B_kmW2ig@mail.gmail.com> References: <7e8459e4-d708-7750-402c-cda2adf6199f@freebsd.org> <CANCZdfqG-%2B9dfFz-%2BeezZaqbPQN5-mQpw%2B214CkiKC%2B_kmW2ig@mail.gmail.com>
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<p>On 06/02/2022 18:20, Warner Losh wrote:<br>
<br>
</p>
<blockquote type="cite"
cite="mid:CANCZdfqG-+9dfFz-+eezZaqbPQN5-mQpw+214CkiKC+_kmW2ig@mail.gmail.com">
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<div dir="ltr">… So there's some tools you can use. For usb,
there's usbdump that can
<div class="gmail_quote">
<div>get you the USB transactions. I've not used it enough to
give more details</div>
<div>here. This will let you know what's going on, and when,
on the USB endpoint.</div>
<div><br>
</div>
<div>You can also enable the CAM_IOSCHED stuff. This will
allow you to get latency</div>
<div>measurements for 'requests in the sim' which basically
will tell you what your</div>
<div>latency spread is for the drives. This will tell you if
things are getting caught</div>
<div>up in the USB layer, or after CAM's da driver completes
the I/O request</div>
<div>(granted, that's almost certainly not happening, but it
will help you figure out</div>
<div>what's going on and put numbers to the oddities you are
seeing).</div>
<div><br>
</div>
<div>Also, make sure you have good cables. I've had lots of
hicups over the</div>
<div>years from dodgy USB cables. Also make sure you have
good, high quality</div>
<div>enclosures. Many from the USB2 time-period are sketchy at
best and I</div>
<div>went through several at one point trying to find a good
one. I'd be tempted to</div>
<div>get USB 3 enclosures. I've had better luck with USB3 gear
than USB2 gear</div>
<div>here, but you need a USB-3 controller to get USB-3 speeds
which might not</div>
<div>be compatible with the NUC's built-in stuff (though my
NUC has one USB3</div>
<div>port, there's lots of different models).</div>
<div><br>
</div>
<div>Usually, though, I see weirdness associated with dmesg
messages from</div>
<div>usb, cam, etc when the hardware is on the sketch end.</div>
<div><br>
</div>
<div>Warner</div>
</div>
</div>
</blockquote>
<p><br>
</p>
<p>Thanks, I'll arm myself with those tools. <br>
</p>
<p>In the meantime (maybe more for freebsd-virtualization@ than
here): where a VirtualBox guest running FreeBSD behaves as if its
boot disk has disappeared, and <i>no</i> exhaustion at the
underlying storage level, is there a sysctl in the guest that
might help to avoid the situation? <br>
</p>
<p><b>Underlying storage</b>: OpenZFS pool on an old but reasonably
good mobile hard disk drive (the one that features in
<a class="moz-txt-link-rfc2396E" href="https://github.com/openzfs/zfs/issues/13038"><https://github.com/openzfs/zfs/issues/13038></a>; with a
hardware probe near the head of the opening post). <br>
</p>
<p>Whilst I have <i>not</i> yet found time to pay all due attention
to VirtualBox logs, I <i>do</i> have a strong sense that these
stalls of guests are <b>more likely to bug FreeBSD guests than,
for example, my Windows 10 guest</b> with its .vhd in the same
underlying pool. <br>
</p>
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