On Mon, Feb 11, 2013 at 2:49 PM, Roy Sigurd Karlsbakk [off-list ref] wrote:

quoted

Why would you plug thousands of dollars of SSD into an onboard
controller? It's probably running off a 1x PCIE shared with every
other onboard device. An LSI 8x 8 port HBA will run you a few
hundred(less than 1 SSD) and let you melt your northbridge. At least
on my Supermicro X8DTL boards I had to add active cooling to it or it
would overheat and crash at sustained IO. I can hit 2 - 2.5GB a second
doing large sequential IO with Samsung 840 Pros on a RAID10.

Those onboard controllers are usually connect to 8x PCIe or similar. Also, those controllers from LSI won't allow TRIM support, which may come in handy…

Be sure to check your motherboard documentation each time though. It
turned out his was connected to a 4x DMI 2.0 bus which I had mistaken
as a DMI 1.0 even after reading the docs. Thats approximately a 4x
PCI. It was still shared with all the other devices on the motherboard
including another 4x slot and gigabit ethernet adapters. Also it
wasn't a very good SATA controller even. You can get onboards that are
decent. I have several builds that come with onboard LSI SAS
controllers. Just those are hooked directly to the northbridge on a
dedicated 4x PCIE.

The LSI RAID doesn't support TRIM, I don't know any hardware
controller that does at yet. I just use them as plain HBAs with md for
the raid. When I get a kernel with the mdtrim patches TRIM will just
magically(hopefully) start working.


-- 
Dave Cundiff
System Administrator
A2Hosting, Inc
http://www.a2hosting.com
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