RELENG_7: zfs mirror causes ata timeout

Stephen M. Rumble stephen.rumble at
Tue Jan 8 15:48:17 PST 2008

Quoting Daniel Eriksson <daniel_k_eriksson at>:

> Stephen M. Rumble wrote:
>> The only interesting bit of evidence I could find is that when these
>> errors do occur, smartctl reports an increase in the
>> Start_Stop_Count
>> field on ad6. ad4, which appears to work fine, doesn't demonstrate
>> this and has a much lower value.
> This looks a lot like the drive momentarily shutting down due to a power
> outage/dip, only to immediately start again.

Well, there's usually a sort of click, perhaps as though the drive is  
parking itself, near when the errors occur. I guess this is it  

> Are you sure the power supplies you've tested are good and powerful
> enough to power your box?

I've tried three supplies. One old, two new. The current one is 300  
watts, the largest was 400 watts and the system uses about 40 idle, 60  
loaded (it's a mobile cpu/chipset). I doubt supplied power is the issue.

> Have you tried replacing the SATA power cables (as well as the actual
> data cables)? Are you using the SATA power connectors that shipped with
> the PSU or a Y-cable with a molex plug? Molex<->molex connections are
> notoriously unreliable (either the plug breaks allowing one of the
> connecting cables to halfway slip out, or the connection is simply not
> electrically sound due to bad tolerances).

I've used both molex<->SATA adapters for the old power supply, as well  
as SATA connectors for the new one. The issues are always the same, it  

I'm starting to lose track of everything I've tried. Just to be sure,  
I'll swap power connections between the drives and see what happens.

Thanks for the input,

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