[OpenIndiana-discuss] Poor relative performance of SAS overSATA drives

[Jason Matthews]

> We've generally used only SAS for our ZFS pools, and will continue to
> do so. However, we're looking at adding some SSDs and those are almost
> exclusively SATA. Do folks see issues mixing SATA SSDs as cache and
> log devices in with SAS disk for hybrid storage pools?


I put my SAS drives in disk shelves (Sanima-SC/Newisys NDS-2240) and my
cache in the system. My config uses an 9205-8e for the shelves, a 9211-8i
for boot disk & L2ARC and an DDRdrive X1 for ZIL acceleration. In general, I
write off non-LSI or non-Marvell on-board disk controllers.

My current line of thinking is anything up to the SAS2008 chipset is
probably too slow to fully a accommodate a system loaded with modern
massively utilized SSDs and drive the storage portion of the pool well if
you have a significant number of disks.

A number of fully utilized SSDs can give disk controllers a solid run for
their money -- forget about putting them behind RAID cards. The next spin of
HP's raid controller is rumored to have a Nehalem processor on it so it can
keep up with SSDs.


On a side note, if you put most SSDs in the an HP p410 RAID, the system
shuts down within a couple of minutes complaining about thermal overloads --
go figure. Likewise, if you put an LSI card into a DL380G7 and plug into the
passive back plane it improperly detects the drive location and on occasion
I believe it fully corrupted disks. While HP may be Solaris friendly, it
doesn't seem to be 3rd party friendly.

BTW, the Seagate Pulsar is SAS. I haven't had the pleasure of giving one a
whirl yet.

j.