[TriLUG] Linux Software RAID experience

[Ron Kelley via TriLUG]

Greetings all,

<hopefully not a duplicate post>

Looking for some feedback with Linux software RAID.  I have a couple of 
servers in a lights-out facility running LSI RAID controllers (2208 
chips) that have been working great for a long time.  Recently, we 
decided to switch out spinning disks for SSDs (8x Samsung 1TB in 
RAID-5).  After getting the RAID volume rebuilt, I noticed slow write 
speeds (about 500MB/secs).  I was expecting at least 1,500MB/secs writes 
given we have 8x SSDs.  No amount of tuning/tweaking the RAID controller 
seems to make a difference.

At this point, I can either purchase better/faster RAID controller 
($500-$700) or switch over to Linux software RAID.  My past experience 
with mdadm left me a little disappointed.  The RAID rebuild times were 
slow and drive swaps were klunky (even after setting speed_limit_min and 
speed_limit_max settings).  At one point, the build/rebuild speeds 
seemed to cap out around 250MB/sec - even with SSDs.

I know mdadm has been around for a very long time, but I am looking for 
some recent usage using mdadm on systems with SSDs.  What tool do you 
use (Rockstor, FreeNAS, etc) to manage the RAID array and what kind of 
performance do you get?  How "turn-key" is it to recover data or replace 
drives?

At the end of the day, I need a turn-key RAID solution - easy enough 
that someone can walk into the facility and replace a faulty drive w/out 
having to dive into a CLI or use a management tool.


Thanks,

-Ron