'ls' hangs FC6

[Mark Haney]

Todd Denniston wrote:
> Mark Haney wrote, On 04/10/2008 02:06 PM:
>> Rick Stevens wrote:
>>> Paul Johnson wrote:
>>>> On Wed, Apr 9, 2008 at 1:26 PM, Mark Haney <mhaney at ercbroadband.org> 
>>>> wrote:
>>>>> Does anyone have any ideas on why 'ls' would suddenly stop working? 
>>>>> I've got
>>>>> a FC6 box that acts as a SAN host and for the last week or so I 
>>>>> can't ls
>>>>> anything.  It sits and does nothing.  Everything else on the box 
>>>>> works just
>>>>> fine except for that.
>>>>>
>>>>>  I've got no idea how to even go about debugging this.
>>>>>
>>>>
>>>> I have seen this on systems that are using LDAP for authentication.
>>>> They don't just authenticate at start time, but they look up user
>>>> information every time.  Every single time any command is run, the
>>>> system goes off to check user identity on a server.  When there is
>>>> network slowdown or server slowdown, then ls is slow.  For us, the
>>>> short term fix was to install the nscd to cache the information so the
>>>> system does not constantly look on the server.  The long term fix was
>>>> to stop authenticating users with LDAP.
>>>
>>> Or run "ls -ln" so you don't do user/group lookups and simply display
>>> the numbers.
>>>
>> It must be something with the user/group lookups then because an ls-ln 
>> works just fine. I just can't figure out /why/ it's a problem now.
> 
> does the ls which hangs, output SOME of the info before it hangs?
> perhaps something like the following could be useful...
> 
> for i in *
> do
>    OPTIONS_THAT_HANG_LS="--color=tty"
>    /bin/ls $OPTIONS_THAT_HANG_LS $i &&  \
>    echo "$i" >> /tmp/files_that_did_not_hang_ls.txt &
> done
> 
> of course you'll have a bunch of ls's hanging when this is done.
> `killall -9 ls` them?
> 
> /bin/ls > /tmp/wholedir.txt
> diff -u /tmp/files_that_did_not_hang_ls.txt \
>     /tmp/wholedir.txt | \
>     grep -e "+" >/tmp/trouble
> 
> then for the files in /tmp/trouble (after looking to see if someone on 
> this list does not pull a flamethrower on Todd for the suggestion)
> for i in $TROUBLEMAKERS
> do
>     #just ignore the problem
>     #chown root:root $i
>     #If that don't fix it, I am at a loss,
>     #or you are loosing hardware.
>     #
>     #try to figure out if it is a consistent user
>     # or group causing the problem.
>     #ls -ln $i
> done
> 
> 
> 
Strangely the system hangs before displaying ANY files.  If it did a 
few, it might be something I could nail down myself.

Now, I'm getting more and more sure that it's a user/group resolution 
problem since the ls -ln option works in every case where both ls and ls 
-l hang.



-- 
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Mark Haney
Sr. Systems Administrator
ERC Broadband
(828) 350-2415

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