[rescue] The State of SunHELP (new server build, etc)

Jonathan Patschke jp at celestrion.net
Mon Jun 10 15:14:45 CDT 2019

On Mon, 10 Jun 2019, Bob Darlington wrote:

> Raidz3 all the way.   There are other under the hood tweaks we use and I'll
> get you the list when I am in the office and remember.

Benchmark your load before going with raidz3.  In order to avoid the
parity "write hole", the I/Os will tend to serialize, which means you'll
usually get throughput limited to the slowest disk in the batch.

For the same reason, tuning recordsize on raidz can make a huge difference
(partial stripe writes with parity make everyone have a rough day).

I've had excellent experience with doing a zpool where each vdev is a
mirror and devices in the mirrors are split between manufacturers (ie:
WDC in the "left" side of each mirror, and Seagate in the "right").

For my "back up the world" box, it's raidz2 over slow disks.  It works
fine, but performance is pretty bad for modern hardware.  For the machine
I run data-crunching jobs on, I have two zpools each with four disks
arranged into two mirrors.

For additional tweaks and tunables, please refer to the quote in my
signature. :)

Jonathan Patschke   |   "The more you mess with it, the more you're
Austin, TX          |    going to *have* to mess with it."
USA                 |                            --Gearhead Proverb

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