'ls' hangs FC6

Todd Denniston Todd.Denniston at ssa.crane.navy.mil
Thu Apr 10 18:24:42 UTC 2008


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



-- 
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane)
Harnessing the Power of Technology for the Warfighter




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