Bug or Feature? -- Disappearing /dev/ nodes after mount
freebsd at edvax.de
Fri Jun 12 07:20:25 UTC 2020
On Thu, 11 Jun 2020 23:54:55 -0700, David Christensen wrote:
> On 2020-06-11 23:22, Polytropon wrote:
> > On Thu, 11 Jun 2020 16:14:09 -0700, Ronald F. Guilmette wrote:
> >> Interestingly, as I have just learned, when and if the user subesquently
> >> mounts the relevant partition, the corresponding `/dev/gpt/partname' node
> >> will, rather unexpectedly and magically, disappear until such time as the
> >> relevant partition is unmounted, whereupon it will reappear.
> >> 1) Is this behavior documented somewhere that I just failed to look at?
> >> If so, where?
> > Interesting question - I would be interested in that, too.
> See Lucas, AF3E, p. 214 "GEOM Withering" .
Wow, thanks for providing the term. techn. "GEOM Withering",
which leads to usable search results, for example:
This GEOM names appearing and disappearing is the
consequence of *GEOM withering. A GEOM can be used
in three different ways:
- with exclusive access
The latter is the cause of GEOM withering: once a
disk is mounted an exclusive lock is required to
inform the other available GEOM providers that the
disk is in-use. GEOM therefore withers the other
disk available names, that results in the names to
disappear from the dev filesystem. For more
information see g_wither_geom(9) and geom(4)
And from that point, local documentation at "man 4 geom" says:
ORPHANIZATION is the process by which a provider
is removed while it potentially is still being used.
When a provider is orphaned, this does not necessarily
result in any immediate change in the topology: any
attached consumers are still attached, any opened
paths are still open, any outstanding I/O requests are
with an explanation of what happens, with additional info
found in "man 9 g_wither_geom".
Today I learned. ;-)
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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