[nycbug-talk] ZFS question

[Isaac Levy]

On Sep 26, 2011, at 9:13 PM, George Rosamond wrote:

> Quick question for the ZFS users in the audience:
> 
> The box in question will have 8 SATA drives on it.  The RAID card (which isn't going to be doing any RAID) has four SATA ports.  There's four more SATA ports on the motherboard.
> 
> Anything I should be concerned about here in terms of performance and data integrity?
> 
> TIA
> 
> George

Cool- I did this a while back when ZFS on FreeBSD was really green, I hacked hw together with as many sata cards as I could dig out- ZFS was itself rough-edged and new back then so my results were, um, a good learning experience :)
The mixed SATA ports themselves didn't seem to cause any particular grief.

If you're concerned about the performance/reliability mixing the ports, I suggest running some tests using good ol' bonnie++.  It sounds tedious, but it's so fast to build/destroy zpools, it's really quite fun and quick.  I would run a straight bonnie++ run on the box in the following configurations and see what suits you:

- All 8 drives as one big zpool
- split drives into 2 pools: 4 on the card, 4 on the motherboard
- a single drive as a zpool

Other fun tests, should you have time/interest:
- raidz vs raidz2
- zfs block-level gzip compression
- atime on, atime off

Sounds like a tall order to test, but it's so easy- since there's no waiting around for newfs to complete...  And if it bombs out, you'll have a chance to see why.

--
The SATA ports should themselves operate normally, still the most important parts for running ZFS: 64 bit cpu, and as much memory as possible.

Here's some more fun notes, lots of hardware/zfs intricacies discussed:
http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide

And for the record, tons of working info on FreeBSD ZFS:
http://wiki.freebsd.org/ZFS

Best,
.ike