ITEM: HE6693L

sysback backup hungs on file /var/locks/cron.lck

Env:
  AIX 4.2.1
  RISC 7043 140  43p
  sysback 4.2.1.2

Problem:
  When the customer does a full system backup using
  the sysback -xf /dev/rmt0  command it hungs about
  97% of the way through.

Action Taken:
  I had the customer using this syntax:
  sysback -vf /dev/rmt0
  It was hunging on the file /var/locks/cron.lck

  cd /var/locks/cron.lck
  It had only the sticky bit set.
  
After some research I found this out:

I determined this is a defect within AIX against 
bos.rte.cron at 4.2.1.2 (IX76281 caused the problem)
.The file /var/locks/cron.lck was created to keep multiple instances
of cron from running.  It was created with bad permissions
of ---S--- or something to that effect.

The permissions should be r--r--r  root.cron
chmod 444 /var/locks/cron.lck
chown root.cron /var/locks/cron.lck

Should be run to correct the problem.  This will occur everytime
the system is rebooted the file will be removed and recreated
with the incorrect permissions.
You can create a /etc/rc.local and add the above entries into it,
then add an entry into inittab.

The problem is not within sysback, but within AIX.
As stated above IX76281 causes the problem.  It creates
a file /var/locks/cron.lck with bad permissions that
effects the tar command.
.The backbyname and backbyinode commands are not effected.
Version 3 of sysback did not give the customer a choice in
which command to use, they used backbyname for the sysback, mkvgback
and mkdirback commands and backbyinode for the mkjfsback.
.At version 4 of sysback the user now could use either tar or
backbyname for their backups.
.I tested this out in the lab.  I installed the fix and started
an instance of cron, so it would create that file "/var/locks/cron.lck"
I checked and it had the permissions of:
------S---   1 root     cron           0 Sep 01 08:17 cron.lck
.I also made sure cron was running against that file
fuser -u cron.lck
cron.lck:     5312(root)
ps -eaf ! grep 5312
root  5312     1   0 08:17:54      -  0:00 /usr/sbin/cron
.I ran:
tar -cvf /dev/null /var
It hung on file /var/locks/cron.lck   (as expected)
.find /var ! backup -ivqf /dev/null
It worked (as expected)
.Workarounds to this problem
change the permissions on that file to r only
chmod 444 /var/locks/cron.lck
.Or you can just remove that file rm /var/locks/cron.lck
.IX79447 - bos.rte.cron 4.2.1.3 fix for cron lock perms
which is not yet been released.



Support Line: sysback backup hungs on file /var/locks/cron.lck ITEM: HE6693L

Dated: September 1998 Category: N/A

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