On Thu, 17 Jan 2013 16:12:17 -0600, Karim Fodil-Lemelin
<fodillemlinka...@gmail.com> wrote:
"SAS controllers may connect to SATA devices, either directly connected
using native SATA protocol or through SAS expanders using SATA Tunneled
Protocol (STP)."
The systems is currently put in place using SATA instead of SAS
although its using the same interface and backplane connectors and the
drives (SATA) show as da0 in BSD _but_ with the SATA drive we get *much*
better performances. I am thinking that something fancy in that SAS
drive is not being handled correctly by the FreeBSD driver. I am
planning to revisit the SAS drive issue at a later point (sometimes next
week).
Your SATA drives are connected directly not with an interposer such as the
LSISS9252, correct? If so, this might be the cause of your problems.
Mixing SAS and SATA drives is known to cause serious performance issues
for almost every JBOD/controller/expander/what-have-you. Change your
configuration so there is only one protocol being spoken on the bus (SAS)
by putting your SATA drives behind interposers which translate SAS to SATA
just before the disk. This will solve many problems.
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