Re: [smartmontools-support] Does smartctl use non-queued commands

[Christian F. <Chr...@t-...>]

Lynn Heinemann wrote:
>
> Hi, I’m not developer by nature but I’m trying to use smartctl against 
> some Intel S3700 SSD drives behind a Dell PERC8 controller and was 
> recently asked the question of whether smartctl uses queued or 
> non-queued commands to query disks.
>

The data transfer commands smartctl uses for ATA/SATA devices are:
IDENTIFY, SMART READ DATA, SMART READ THRESHOLDS, SMART READ LOG, SMART 
WRITE LOG, READ LOG EXT.
All of these use the "PIO Data-In/Out" ATA protocols which are 
non-queued. Queued versions of these commands do not exist.


> The concern was a system under very heavy write load and we want to 
> monitor the disk health during production, if we were to run smartctl 
> commands against the disk, would it use a non-queued command and 
> possible abort the queue causing possible data loss or corruption?
>

This should never happen if the ATA pass-through functionality 
(including possible SAT Layer) in the controller driver and firmware is 
properly implemented. The firmware should wait until the queue is empty 
before issuing any command received via a pass-through I/O-control.


> I’ve been looking over the FAQs for smartmontools and reading through 
> what I can find on Github but I’m not familiar enough with the tools 
> to have a solid confirmation.
>

Note that any smartmontools code on github is an independent project. 
The official code is in the SVN repository at sourceforge.
It could be viewed here: https://www.smartmontools.org/browser

Thanks,
Christian