[petsc-users] osx error

[Satish Balay]

On Fri, 18 Sep 2020, Satish Balay via petsc-users wrote:

> > >> 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]

BTW: To confirm, please try:

ping 127.0.0.1

Satish

> 
> 
> 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/>
> > >
> > 
>