[OmniOS-discuss] Configuration sanity checking

[Chris Siebenmann]

> > > Motherboard - Supermicro X10DRi family
> > > CPUs - E5-2620 v3
> > > HBA - LSI 9300-8i
> > > Network - Intel i350 or 540, depending on precise motherboard variant
> > > Disks (SSD) - Intel S3510 (boot), S3610 (application + data)
> >
> > The drives are SATA and there are quite a few SATA ports on the
> > mobo, do you need the SAS HBA?
>
> So that was an interesting question, and I had to go away and
> investigate further.  So the way this works is that the system has a
> 24-slot disk backplane. The disks plug into the backplane; you have
> to connect the backplane as a unit to something, which is where the
> HBA comes in. It doesn't look like there's a way to wire an individual
> drive to an onboard SATA port.

 It may be possible to do this, especially if this is a SuperMicro
case. SuperMicro (and probably other people) generally offers several
backplane options. One of them passes each disk through the backplane as
a separate connection, although connections will usually be aggregated
together in IPASS/SFF 8087 connectors (which bundle 4 SAS ports into one
cable and connector).

 Once you have IPASS connectors on your side of the backplane, I
think that you can get IPASS-to-plain-SATA cables; these have an
IPASS connector on one side that splits out to four SATA cables and
connectors. I believe that this would allow you to use four motherboard
SATA ports to talk to four drives on the other side of the backplane via
plugging the IPASS side into one of the backplane's IPASS connectors.

 In the long run you are definitely going to need some HBAs to talk
to all of those drives, though. Your motherboard probably does not
have enough onboard ports.

(We have a 24-disk SuperMicro chassis set up like this, although it
doesn't run OmniOS. The disks are connected via an on-motherboard LSI
SAS2308 and a LSI SAS2116 card; the former runs 8 drives via 2x IPASS
connectors, the latter 16 via 4x IPASS.)

 Like other people, I feel that you probably don't want to run SATA
drives through a SAS expander (ie, using fewer SAS ports than actual
drives). Almost everything I've heard about this doesn't sound good, and
I like the simplicity of 'one drive, one port'.

	- cks
[This whole area is tangled and confusing. When I was digging into
 it several years ago I wound up writing down what I worked out about
 the whole situation here:
	https://utcc.utoronto.ca/~cks/space/blog/tech/SASWithSATAIntro
]