Linked by Thom Holwerda on Thu 12th Jan 2012 22:54 UTC
FreeBSD Some people already submitted this news last week, but it wasn't until today that it became official: the FreeBSD team has announced the release of FreeBSD version 9.0. As you may expect from the major version number change, this is releas eis packed with new stuff.
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RE[2]: Time to give it a try
by phoenix on Fri 13th Jan 2012 19:30 UTC in reply to "RE: Time to give it a try"
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We've been using ZFS since it hit 7-STABLE way back when. Other than some growing pains around memory usage and poor vdev setup (don't do a single 24-disk raidz2!!), things have been very stable.

We just put into production 2 FreeBSD 9.0 storage boxes (one upgraded from 8.2, the other clean install of 9.0) using raidz2, lzjb compression, and dedupe. These are backups boxes running our custom rsync scripts to backup over 150 servers every night, creating snapshots every morning, and pushing the data to an offsite server during the day.

The things to note for using ZFS on FreeBSD:
- use 64-bit hardware and version of FreeBSD
- stick as much RAM as you possibly can into it
- use the fastest drives you can afford (avoid Green drives)
- be sure to stick an SSD in the system for use as L2ARC (read cache)
- if you can afford a fast SSD, use it for SLOG (write cache)

If you are going to play with dedupe, you need at least 16 GB of RAM, preferably more. And your RAM needs will only increase as you add data to the pool (the rough calculation is about 1 GB of RAM per TB of deduped data in the pool). You can use an L2ARC device to lower the RAM requirements, but that only helps so much.

If you want performance, go with mirror vdevs. If you want storage space, go with raidz2 (or even raidz3) vdevs with small numbers of drives per vdev (keep it under 10). The more vdevs in the pool, the better the overall performance of the pool (meaning a 24-disk pool using 1 raidz2 vdev will be much slower than a 24-disk pool with 4x 6-drive raidz2 vdevs).

It may take a little tuning of /boot/loader.conf settings to make things perfectly stable, although the auto-tuning in 9.0 has improved a lot. All we set now is the vfs.zfs.arc_max to about 80% of RAM.

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