Steve Cousins wrote:
* What chunk size should I use? In previous RAID 5 arrays I've built
for similar purposes I've used 512K. For the setup I'm describing,
should I go bigger? Smaller?

It is best to try a number of different configurations and benchmark
each one to see how it works with your needs. For my needs I've mainly
used 64 KB stripes because it gave better performance than 128 or
higher.

I figured as much, but was hoping that someone else would say "Hey, in
my experience ___KB chunks are best for your situation, and I'd raise
the chunk size ___KB for every terabyte bigger." I guess there's just
no way around manually building and rebuilding the array a few times,
unless the performance with each chunk-size step relative to with
others is the same as while the array is still dirty and being built
up for the first time and once the array is finished.

Make sure you match the file system chunk size to the RAID stripe
size too.

I don't think this is an issue with JFS; that is, mkfs.jfs doesn't
offer any such options in the first place.

For this many SATA drives I would hope that you are going with RAID6
and a hot-spare.

Undecided. While the recordings would be inconvenient to lose, it
would not be life-or-death. I suspect I'll end up doing RAID 6 but no
hot spare.

In my previous such array (see below) I went to the trouble of buying
an extra drive for cold swap which, naturally, hasn't ever been
needed. Given the enterprise-class Western Digital drives I'm using
this time I shouldn't have any trouble hunting down an exact spare or
two in three or five years' time; worst comes to worst I'd just buy a
750GB for whatever ridiculously-low price they sell for then and just
not use the extra space in the array.

--
URL:http://www.pobox.com/~ylee/ PERTH ---- *

Homemade 2.8TB RAID 5 storage array:
URL:http://groups.google.ca/groups?selm=slrnd1g04a.5mt.ylee%40pobox.com