[petsc-users] osx error

[Satish Balay]

> >> 07:41 master *= ~/Codes/petsc$ ping -c 2 MarksMac-302.local
> >> PING marksmac-302.local (127.0.0.1): 56 data bytes

So it is resolving MarksMac-302.local as 127.0.0.1 - but ping is not responding?

I know some machines don't respond to external ping [and firewalls can block it] but don't really know if they always respond to internal ping or not.

If some machines don't respond to internal ping  - then we can't use ping test in configure [it will create false negatives - as in this case]


Mark, can you remove the line that you added to /etc/hosts - i.e:

127.0.0.1 MarksMac-302.local

And now rerun MPI tests. Do they work or fail?

[this is to check if this test is a false positive on your machine]

Satish


On Fri, 18 Sep 2020, Mark Adams wrote:

> On Fri, Sep 18, 2020 at 7:51 AM Matthew Knepley <knepley at gmail.com> wrote:
> 
> > On Fri, Sep 18, 2020 at 7:46 AM Mark Adams <mfadams at lbl.gov> wrote:
> >
> >> Oh you did not change my hostname:
> >>
> >> 07:37 master *= ~/Codes/petsc$ hostname
> >> MarksMac-302.local
> >> 07:41 master *= ~/Codes/petsc$ ping -c 2 MarksMac-302.local
> >> PING marksmac-302.local (127.0.0.1): 56 data bytes
> >> Request timeout for icmp_seq 0
> >>
> >> --- marksmac-302.local ping statistics ---
> >> 2 packets transmitted, 0 packets received, 100.0% packet loss
> >> 07:42 2 master *= ~/Codes/petsc$
> >>
> >
> > This does not make sense to me. You have
> >
> >   127.0.0.1 MarksMac-302.local
> >
> > in /etc/hosts,
> >
> 
> 09:07  ~/.ssh$ cat /etc/hosts
> ##
> # Host Database
> #
> # localhost is used to configure the loopback interface
> # when the system is booting.  Do not change this entry.
> ##
> 127.0.0.1 localhost
> 255.255.255.255 broadcasthost
> 127.0.0.1    MarksMac-5.local
> 127.0.0.1 243.124.240.10.in-addr.arpa.private.cam.ac.uk
> 127.0.0.1 MarksMac-302.local
> 09:07  ~/.ssh$
> 
> 
> 
> 
> 
> > but you cannot resolve that name?
> >
> >   Matt
> >
> >
> >> BTW, I used to get messages about some network issue and 'changing host
> >> name to MarksMac-[x+1].local'. That is, the original hostname
> >> was MarksMac.local, then I got a message about changing
> >> to MarksMac-1.local, etc. I have not seen these messages for months but
> >> apparently this process has continued unabated.
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> On Thu, Sep 17, 2020 at 11:10 PM Satish Balay via petsc-users <
> >> petsc-users at mcs.anl.gov> wrote:
> >>
> >>> On Thu, 17 Sep 2020, Matthew Knepley wrote:
> >>>
> >>> > On Thu, Sep 17, 2020 at 8:33 PM Barry Smith <bsmith at petsc.dev> wrote:
> >>> >
> >>> > > > On Sep 17, 2020, at 4:59 PM, Satish Balay via petsc-users <
> >>> > > petsc-users at mcs.anl.gov> wrote:
> >>> > > >
> >>> > > > Here is a fix:
> >>> > > >
> >>> > > > echo 127.0.0.1 `hostname` | sudo tee -a /etc/hosts
> >>> > >
> >>> > >  Satish,
> >>> > >
> >>> > >    I don't think you want to be doing this on a Mac (on anything?)
> >>> On a
> >>> > > Mac based on the network configuration etc as it boots up and as
> >>> networks
> >>> > > are accessible or not (wi-fi) it determines what hostname should be,
> >>> one
> >>> > > should never being hardwiring it to some value.
> >>> > >
> >>> >
> >>> > Satish is just naming the loopback interface. I did this on all my
> >>> former
> >>> > Macs.
> >>>
> >>>
> >>> Yes - this doesn't change the hostname. Its just adding an entry for
> >>> gethostbyname - for current hostname.
> >>>
> >>> >>>
> >>> 127.0.0.1 MarksMac-302.local
> >>> <<<
> >>>
> >>> Sure - its best to not do this when one has a proper IP name [like
> >>> foo.mcs.anl.gov] - but its useful when one has a hostname like
> >>> "MarksMac-302.local" -that is not DNS resolvable
> >>>
> >>> Even if the machine is moved to a different network with a different
> >>> name - the current entry won't cause problems [but will need another entry
> >>> for the new host name - if this new name is also not DNS resolvable]
> >>>
> >>> Its likely this file is a generated file on  macos  - so might get reset
> >>> on reboot - or some network change? [if this is the case - the change won't
> >>> be permanent]
> >>>
> >>>
> >>> Satish
> >>>
> >>
> >
> > --
> > What most experimenters take for granted before they begin their
> > experiments is infinitely more interesting than any results to which their
> > experiments lead.
> > -- Norbert Wiener
> >
> > https://www.cse.buffalo.edu/~knepley/
> > <http://www.cse.buffalo.edu/~knepley/>
> >
>