One way to put it is that in system administration, an issue that takesall of your time and energy for a week is a big thing and one that takesa month is generally a crisis. The same generally cannot be said ofprogramming except at a very small level; while you may clearly be goingup steps, the top of the path is generally not in sight.

Or in other words, you accomplish visible things much faster in systemadministration, and this gives you real, tangible signs of progress and

To follow up the first installment , it turns outthat enabling the source repositories has a side effect that I didn'tthink about at the time: it no longer looks in the default repositories.

(This is a general thing in yumdownloader : any time you specify arepository explicitly, it disables all the default ones. This makesme grumpy. While you can argue that this makes a sort of sense, itis not how yum itself behaves when you enable repositories, and yumdownloader uses the exact same command line

Now that we know how NFS is unreliable , we cansee what can go wrong when you attempt to do file-based locking over NFS. There are two failures, corresponding tothe two ways for things to go wrong when a reply is lost:

• if you lose the server's reply to a successful attempt to acquirethe lock, your replay of the operation will report a failure even thoughyou actually own the lock. The result is effectively a deadlockedsystem where the lock will never get released.

  (This