RPI3 swap experiments, was Re: GPT vs MBR for swap devices

bob prohaska fbsd at www.zefox.net
Tue Jun 26 14:43:11 UTC 2018

On Tue, Jun 26, 2018 at 11:40:11AM +0100, Jamie Landeg-Jones wrote:
> Warner Losh <imp at bsdimp.com> wrote:
> > > > _vfs_done():da0d[WRITE(offset=51819347968, length=131072)]error = 5
> > > > g_vfs_done():da0d[WRITE(offset=51819479040, length=28672)]error = 5
> > > > g_vfs_done():da0d[READ(offset=59586936832, length=32768)]error = 5
> > > > g_vfs_done():vm_fault: pager read error, pid 823 (tcsh)
> > >
> >
> > The device is broken if you get this. Period. I don't know if it is
> > hardware, or software, but it is not a reliable storage device. Until
> > that's fixed, you'll continue to have a terrible experience with it.
> >
> [ ... ]
> > Sorry to sound so harsh, but the data has been consistent on this for
> > everything you've reported: it works for a while, then we get a bunch of
> > errors then a reboot. We need to start narrowing down which of these three
> > broad classes of root causes it is. I'd rank actual bad thumbdrive last on
> > the list. It's a tossup for me between missing quirk and a bug in the rpi
> > usb driver that manifests itself only under heavy load. IIRC, you said one
> > of rpi2/3 works and the other doesn't, which would suggest a usb bridge
> > driver problem...
> For what it's worth, I had the same errors on a rpi3 a few months ago, and
> eventualy gave up "to sort it tomorrow" - it hasn't been powered on since, but
> I still want to get it working.
It might be worth quite a lot 8-)

> The system would run fine, but give the vfs errors on the 128GB usb thumb
> drive every week - like clockwork, when one of the heavier periodic jobs ran.
That is something I've not seen.
> I was running the latest CURRENT at the time. The thumb drive works fine elsewhere,
> and indeed - did on the same hardware when I test installed a linux install,
> and thrashed the hell out of it.
> I'll fire it up again - hopefully I'll still have the same results, and with 2
> of us, we may find the cause quicker.
> (n.b. i never had swap errors, but I can't recall if i ever configured swap on the usb
> drive)
To be clear, the USB thumb drive in question wasn't supporting a swap partition at the
time of the error message quoted above. /da0d held /usr. Swap was on the boot microSD 
card and was deliberately too small (1 GB) to let -j4 buildworld run to completion. 
All attempts to use swap on the suspected USB flash drive resulted in OOMA kills, 
all attempts to use sufficient swap (2 GB or more) not on the suspected USB flash 
drive resulted in successful -j4 buildworlds.

Thanks for writing!

bob prohaska

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