Short SMART check causes disk op timeouts

Jeremy Chadwick koitsu at
Mon Oct 27 12:10:33 PDT 2008

On Mon, Oct 27, 2008 at 07:52:01PM +0100, martinko wrote:
> Jeremy Chadwick wrote:
>>>>> Now, does the timeout cause loss of any data? Is there anything besides
>>>>> disabling the testing that I can do about it?
>>>> Do you understand what short and long offline tests actually do and what
>>>> they're used for?  :-)  If so, you'd know that running them periodically
>>>> is more or less silly (IMHO).
>>> I do not, not completely :) I think I have just copied the settings from
>>> somewhere and only just tweaked it a bit whenever I have added a disk.
>> Let me know if you figure out who or what online resource solicited
>> adding daily short/long tests, as I'd like to talk to them about their
>> decision.  I have a feeling whoever thought it up felt that the tests
>> were performing entire sector scans of the entire disk, which is simply
>> not the case.
> Hallo,
> Reading this thread I checked my config to find this: ;-)
> #/dev/ad0 -a -n standby,q -o on -S on -s (S/../.././02|L/../../7/03) -m  
> root    # ++ 2006-11-03 mato
> /dev/ad0 -a -o on -S on -s (S/../.././02|L/../../7/03) -m root  # ++  
> 2006-11-03 mato
> I believe I came up with the settings after reading manual page /  
> documentation of the tool.

Can you explain why you're doing this?  So far no one's provided a
reason *why* they're doing short and long offline scans on a daily
basis.  I'm under the impression the conclusion was reached like this:
"man smartd.conf ... oh, -s, a neat thing, let's enable it".

There are negative repercussions to doing tests of this nature at such
regular intervals.  Once-a-week is borderline acceptable; once a month
would be quite reasonable.  I'd love to know what kind of affect daily
tests have on MTBF; I can imagine it's reached much sooner with this.

The main point of smartd is to monitor SMART attribute changes.  If
you're concerned about the health of your hard disk, you should be
looking at your logs and not relying on things like automatic short/long
tests.  Most SMART attributes are updated immediately and not during an
offline test, and all of those attribute changes will be logged.

| Jeremy Chadwick                                jdc at |
| Parodius Networking              |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |

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