On 12/15/2015 02:44 PM, Dallas Clement wrote:

Wow!  Thanks a ton Phil.  This is incredibly helpful!  It looks like I
need to do some experimenting with smaller chunk sizes.  Just one more
question:  what stripe cache size do you recommend for this system?
It has 8 GB of RAM, but can't use all of it for RAID as this NAS needs
to run multiple applications.  I understand that in the >= 4.1 kernels
the stripe cache grows dynamically.

I don't really know.  I use the default 256, but all of my parity raid
arrays have 16k chunks and are relatively lightly loaded.  Consider
sampling stripe_cache_active once a second for a normal workday on real
workloads to figure out what you need.

Phil