[OmniOS-discuss] SATA SSD vs. SAS

Nate Smith nsmith at careyweb.com
Mon Sep 29 20:10:55 UTC 2014


Recently purchased a large number of 480GB datacenter grade SSDs with the idea to make a ZPOOL for a VM infrastructure. After receiving, I realized that they are SATA and not SAS, and that I'd completely overlooked that fact. I was planning on using them in a DELL R720XD which only uses two SAS cables for 24x2.5" disks.  Since this backplane is obviously a SAS expander/multiplier, it will probably lead to disastrous results with SATA drives. Everything I've read says "don't use SAS expanders with SATA drives." (not to mention, that I'll completely saturate the data paths with these).  In that vein, I've got a few  questions.

People choose SATA for SSD, because when it comes to SSD, the price may be 4-10 times as much for SAS. I've seen lots of setups with SAS spinning disks and SATA for L2ARC or ZIL.  How are people connecting SATA disks for just these tasks and avoiding problems? Straight onto the SATA port on the motherboard?  Are there any SATA only controllers that work well for SSD on Omnios?

Does anyone know of any JBODs that are expander/multiplier free that would work for this setup? I have had a hard time finding any.

Has anyone had any luck with interposers? I read this report, and it sounded promising till I got to the end. 
http://xnat.org/blog/xnat-hardware/rsf-1-high-availablity-ssd-pool-for-vm-storage-and-build-space/

Thanks in advance,

--
Nate Smith



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