Re: two /net paths to the same local mount?

[Chris Quenelle <chris.quenelle@oracle.com>]

Ian,

Thanks again for your help.
I have syslog-ng installed, and I can't figure out how to tell
if "daemon.*" is being sent somewhere or not.  "daemon" doesn't
appear anywhere in /etc/syslog-ng/syslog-ng.conf

But when I grep /var/log/messages I see:

% grep automount messages
Jun 29 02:41:14 carabas automount[11786]: lookup_mount: lookup(yp): key "Codemgr_wsdata" not found in map
Jun 29 02:41:14 carabas automount[11786]: lookup_mount: lookup(yp): key "Codemgr_wsdata" not found in map
Jun 29 03:17:45 carabas automount[11786]: lookup_mount: lookup(yp): key "opt" not found in map
Jun 29 03:24:27 carabas automount[11786]: lookup_mount: lookup(yp): key "Codemgr_wsdata" not found in map
Jun 29 03:24:27 carabas automount[11786]: lookup_mount: lookup(yp): key "Codemgr_wsdata" not found in map
Jun 29 09:04:46 carabas automount[11786]: Debug logging set for /net
Jun 29 09:09:22 carabas automount[11786]: get_pkt: message pending on control fifo.
Jun 29 09:09:22 carabas automount[11786]: Basic logging set for /net

I didn't get the get_pkg message until I turned off debug logging.

While logging was set to debug, I tried the hanging ls command again, and
I also tried listing a different file system that was actually remote.
I didn't see any log messages for those operations.

Notes:

1. /etc/host.conf says only:
      order hosts, bind
      multi on

2. No mount.nfs processes are running when the ls command hangs
   on the local mount.


Ian Kent wrote:
> On Wed, 2010-06-23 at 11:32 -0700, Chris Quenelle wrote:
>> Thanks for your time guys!
>>
>> It turns out it's not a general bug.  I was just applying
>> a pessimistic interpretation without checking.
>>
>> After more testing, it turns out it's just problem
>> on one machine, for two mount points under one
>> host alias.
>>
>> I'm interested in knowing more about how I could
>> debug the situation without just rebooting and
>> hoping it doesn't happen again.
>>
>> Here's my scenario:
>>
>> I have three exported filesystems.
>> I can use three host aliases to refer to my own machine.
>> (carabas, carabas.sfbay, carabas.sfbay.sun.com)
>>
>> /etc/hosts says:
>> [IP addr]     carabas.sfbay.sun.com carabas
>>
>>
>> All filesystems work under all /net/foo aliases
>> except two of them hang when accessed via one
>> of the host aliases.
> 
> Are you sure the address lookup is returning what you think it does?
> What's in /etc/host.conf?
> 
>> % showmount -e localhost
>> Export list for localhost:
>> /export/home3 *
>> /export/home2 *
>> /export/home1 *
>>
>>
>> % df -kl
>> Filesystem           1K-blocks      Used Available Use% Mounted on
>> /dev/sda2             69575344   3408900  66166444   5% /
>> udev                   8222568       148   8222420   1% /dev
>> /dev/sdb1             71671728  26507132  45164596  37% /export/home1
>> /dev/sdc1             71671728   8545196  63126532  12% /export/home2
>> /dev/sdd1             71671728   5375672  66296056   8% /export/home3
>> /export/home1         71671728  26507128  45164600  37% /net/carabas/export/home1
>> /export/home2         71671728   8545196  63126532  12% /net/carabas.sfbay/export/home2
>> /export/home1         71671728  26507128  45164600  37% /net/carabas.sfbay/export/home1
>> /export/home3         71671728   5375672  66296056   8% /net/carabas.sfbay/export/home3
>> /export/home1         71671728  26507128  45164600  37% /net/carabas.sfbay.sun.com/export/home1
>> /export/home2         71671728   8545196  63126532  12% /net/carabas.sfbay.sun.com/export/home2
>> /export/home3         71671728   5375672  66296056   8% /net/carabas.sfbay.sun.com/export/home3
>>
>>
>> % strace ls /net/carabas/export/home2
>> ...
>> ...
>> mmap(NULL, 217016, PROT_READ, MAP_SHARED, 4, 0) = 0x2b2388370000
>> close(4)                                = 0
>> close(3)                                = 0
>> open("/net/carabas/export/home2", O_RDONLY|O_NONBLOCK|O_DIRECTORY <unfinished ...>
> 
> What does a ps listing give you when it is blocked?
> Any mount.nfs processes?
> 
> That's sign that automount thinks that the mount isn't local and is
> probably trying to mount from a possibly non-existent ip address.
> 
>> I hit ctrl-C when the ls command hangs.  Above is the tail of the strace output.
>> It doesn't tell you much, the interesting stuff happens in the automounter.
>>
>> Is there a error log file for the automounter that is enabled by default?
>> Is there an easy recipe for restarting the automounter with debugging output on?
> 
> You need to ensure that debug logging is being recorded in syslog.
> Ensure you are sending daemon.* somewhere.
> 
> Then
> 
> automount -l debug /net
> 
> will start the debug logging and
> 
> automount -l err /net
> 
> will set it back to no logging.
> 
> That is depending on the version of autofs you are using.
> 
> If you don't see this option in the automount(8) man page you don't have
> this option and all you can do is enable debug logging in the
> configuration.
> 
> Ian
> 
>