[wplug] Question about smartmontools

[Mike Sussman]

Folks,
My short question is, "If an extended SMART self-test reports 'Completed
without error,' does that mean the drive is reliable, even if an earlier
self-test failed?"

More detail:  About two months ago, I  noticed something (I forget what)
that made me wonder about the hard drive on my laptop.  The hard drive is a
Seagate  ST9750420AS.  At that time, I ran a self-test using the command
sudo smartctl -t long /dev/sda.  The result was a read failure at LBA
816349744.  I immediately ordered a replacement drive, but the computer was
running OK and I was very busy, so I kept on using it without problem.
About a week ago I installed the new disk and used dd to clone it (same
drive model).  (Not surprisingly, my dual-boot W7/Kubuntu system on the
cloned disk worked fine.)

On a lark, I re-ran the self-test, and it showed no errors!  The log reads:
=== START OF READ SMART DATA SECTION ===
SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining
LifeTime(hours)  LBA_of_first_error
# 1  Extended offline    Completed without error       00%
5813         -
# 2  Short offline       Completed without error       00%
5811         -
# 3  Extended offline    Completed: read failure       90%
5378         816349744
# 4  Extended offline    Aborted by host               90%
5377         -
# 5  Short offline       Completed without error       00%
5377         -
# 6  Short offline       Completed without error       00%
3466         -
# 7  Short offline       Completed without error       00%
1642         -
# 8  Short offline       Completed without error       00%
588         -
# 9  Short offline       Completed without error       00%
0         -
#10  Short offline       Completed without error       00%
0         -
#11  Short offline       Completed without error       00%
0         -
1 of 1 failed self-tests are outdated by newer successful extended offline
self-test # 1

My question, then, is how do I interpret these results?  The internet seems
to say that a good test guarantees a good drive, but I wonder.  Shall I
remove the drive and hammer a spike into its heart?  Shall I regard it as
reliable and use it as a second hard drive on my system?  Shall I continue
to use it, but only for non-critical files (swap, for example)?  Advice and
comments are welcome.