SiI 3124 and Re: External SATA JBOD

[Dieter]

>> I am thinking about adding an external Case with 4 haddrives to my 
>> server that should not be running 247. In ancient times this was done 
>> via SCSI and simply worked (turn on, rescan SCSI, mount).

I suppose you could still use SCSI today if you don't mind paying
$C$I price$.

If the only reason for wanting an external box is the ability to
power the drives down, you could make a custom power cable with a
switch inline.  There are panels with switches that fit standard
3.5" bays, so you don't have to do any metalwork, just a little
soldering.

If an additional SATA drive appears, does the FreeBSD kernel notice
and handle it (like USB) ?  Is a rescan needed (like SCSI) ?  A reboot?

>> I already have an external drive connected via USB, but I am not able to 
>> read SMART using this link.

Another issue with the USB bridges is you can't turn the disk's write
cache on and off.  :-(

Do firewire bridges allow access to the write cache control bit, and SMART data?
How is FreeBSD support for firewire disks?

> I did something similar with an Addonics 4-drive housing and a SiI 3124 based
> SATA controller. That meant writing some of the driver for the 3124, but it
> was fun (and the Soren did the heavy lifting).

Does this mean that the SiI 3124 device driver is working?  Is it
"ready for prime time"?  I've been watching -hardware and -drivers but
haven't seen anything.

> I don't think PM is supported yet. Certainly not in 6-STABLE, possibly in 7.
> I remember Soren was delaying PM work until NCQ was in;

So NCQ isn't ready yet?  :-(

Are there *any* controllers with working NCQ support?

> I had PM support
> without NCQ in 6-STABLE at one point, but that severely limits the total
> throughput of the drives.

I would think that SATA-300 could support 4 drives without slowing them
down, is there some other bottleneck?