gmirror HD failure detection

[Alex Zbyslaw]

Robin Becker wrote:

> Dave wrote:
>
>> Hi,
>>    I've got smartd going on a gmirror system, however when smartd 
>> starts up it says it can't find the various drives. I've tried both 
>> the autodetection line as well as specifying the individual drives. 
>> If this does work i'd like to know about it as i believe i might have 
>> one failing drive, but am not sure which one.
>> Thanks.
>> Dave.
>>
>
>
> well as root I can certainly run smartctl -a /dev/ad4 (or /dev/ad6) so 
> I assume smartd could.
>
> I like the idea of using gmirror status -s , but I don't know what the 
> results would be if one of the disks were going bad. Would it change 
> from COMPLETE to DEGRADED suddenly?

I would expect gmirror to report a problem when a disk gad *gone* bad.  
Going bad from a SMART point of view can mean, for example, too high a 
rate of read retries or too many bad sectors remapped.  At that point 
the drive is technically working, so there is nothing technically wrong 
with the array status.  In such a case SMART would just be telling you 
that the disk is likely to go kablooey soon; time for backups, new drive 
etc. etc.

Something like gmirror status -s you can presumably run even every five 
minutes from cron; if you weed out the good results you'll only get 
email if something does go wrong.

Use both approaches since they tell you different things which just 
happen some of the time to coincide.

--Alex