[OpenIndiana-discuss] dell r730xd + SATA

[Nikola M]

On 04/28/17 09:09 PM, jason matthews wrote:
>
>
> Is anyone using the R730XD with its 3x port expanders successfully
> with SATA drives? Yes, I am aware of the conventional wisdom.

I'll pass some general knowledge, that may not be suitable for your
exact hardware, but could be used as the pointers when you compare your
specs.

Using SAS port expanders is unadvised because they include chips in them
that can go crazy (with their own small firmwares), and with expanders,
the disk controller is not in direct control of the drives and that can
do really bad for ZFS.
That goes especially if using SAS expanders with SATA drives, like a
nightmarish situation, the worst case, that is actually not supported
under illumos. (And especially mixing SAS and SATA drives on the same
SAS expander)
Even using SATA drives with SAS controller on direct ports, without
expanders, is discouraged and not a good idea.
SAS controller -- SAS drives.  SATA controller - SATA drives.

The controller is best to be working in JBOD mode. Don't use Hardware
RAID levels, use controllers that can do JBOD. (Take care, since JBOD
usually gets intentionally disabled on Hardware RAID controllers, so you
have a vendor lock-in for their hardware..) 
Software RAID is what ZFS is for, to elevate one from hardware
constrains. So you can just pop up disks from one machine and pop them
in into another JBOD machine and it just works without any
configuration. (even between x86 and SPARC - ZFS is endian agnostic).
Not possible with hardware RAID controlling drives.

> I have a number of R730s working with the 2x expanders and Intel DC
> S37{0,1}0 SSDs. It is time to order again and the 24 bay 730XD is a
> seductress in terms of storage options. I just dont know if it will
> work well mixing expanders and SATA.

No it won't. It might look ok, or you could seem happy, but at the first
sign of trouble or reporting some bug, you could learn the hard way,
that is not supported configuration to use SATA drives with SAS
expanders. And avoid configuration with the expanders at all, but do
direct connecting drives to the controller ports).

Btw, internet is full with expander warnings, hope this helps.