RFC: ATA to CAM integration patch (and gjournaled previuos nodes)

Alexander Motin mav at FreeBSD.org
Tue Jul 7 19:06:28 UTC 2009

Harald Schmalzbauer wrote:
> One thing I'm missing is the possibility to spin down the drive.
> I have my system on a SSD, the HD is just for ports nad stuff which 
> usually I don't make use of.
> Is that planned to be integrated?

There is no problem, it just wasn't done yet. It should be possible to 
submit respective ATA command via CAM pass interface to spin-down drive 
immediately or to set wanted power management level, but respective 
user-level part in camcontrol is also not implemented yet.

> Another question is why "camcontrol tur ada0" returns "Unit is not ready"
> readcap also doesn't work.

It is all SCSI commands. This implementation expects real direct ATA 
operation without SCSI emulation parts. But this commands should work 
for ATAPI devices, that are really SCSI deep inside.

> My SSD reports write and read cache present, but disabled. Is the report 
> or the status bad?
> Feature                      Support  Enable    Value           Vendor
> write cache                    yes    no
> read ahead                     yes    no

It is probably the truth. Existing ATA driver enables this features 
during drive reset sequence. New one doesn't do it yet.

Alexander Motin

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