Hi ToddAndMargo!

 On 2015.04.10 at 17:21:07 -0700, ToddAndMargo wrote next:

> I have a customer interested in high end workstation. She wants RAID 1 to
> protect her drives. She is also interested in Solid State Drives.
> (And she knows the difference between RAID and Backup.)
> 
> What host controller would you guys recommend for a pair of Intel
> SSDSC2BW480A401, 480 GB 2.5" Internal Solid State Drives in RAID 1?

If you really have no choice in picking any non-SF based SSD, then I
would only recommend software RAID with mdadm. It supports TRIM.
Otherwise you're going to live with eventual performance degradation,
because hardware controllers (at least LSI and Adaptec) do not support
TRIM for drives in RAID. You can google yourself on many reports on how
performance drops for SandForce SSDs filled with data in absence of
TRIM (you may also google about difference between background GC and
foreground GC). It's not pretty.

If you *do* have a choice in this (way, way more important than picking
controller) matter, pick an SSD from other vendor which supports
background garbage collection without TRIM and performance doesn't
degrade even in absence of TRIM. There are so many options and most
vendors put in description that these SSDs are OK to use in RAID or
other environment without TRIM support. These include Marvell-based SSDs
(Plextor M series, Crucial M/MX series and many others), Samsung SSDs
and really many others. If you want to pick SSD for RAID make sure to
check some review which covers performance degradation without TRIM.

It's not to say that Intel SSDs are bad (some are among very best, but
they are expensive enterprise-focused models), but these particular
consumer models based on SandForce controllers do not play that good
with random RAID controller. They are okay to use in software
(mdadm)-based RAID or on Intel software RAID (in Windows) because these
support TRIM, also there were specialized RAID-on-board PCIe SSDs based
on them which supported TRIM also, but you aren't going to get it with
any random controller.

Now, as long as you are using non-SF based SSD, you can among various
RAID controllers. It's probably easier to list ones which aren't
supported.. Good vendors (proven with years) include LSI and Adaptec,
basically you can pick nearly any controller with RAID support from
these vendors and it will work fine. Note that many other vendors like
Intel or Dell sell controllers based on LSI models, often cheaper than
originals. While there are occasional glitches (e.g. my favorite low-end
RAID controller LSI 9211-8i with buggy P20 firmware, had to downgrade),
usually they work great. But really there are tons of options, e.g. if
you are using Dell or HP workstation you can go with controller from
these vendors (Dell will likely to be LSI-based), they work great as
well. It's your choice.

(myself, for simple cases like two-disk RAID1 or four-disk RAID10 I
always just use software RAID :P)

-- 

Vladimir