ZFS practical application?

David Brodbeck gull at gull.us
Tue Aug 10 17:24:41 UTC 2010

On Aug 9, 2010, at 3:40 PM, Ed Flecko wrote:

> Hi folks,
> I've been reading about the ZFS file system, and I'm having a hard
> time understanding maybe the most practical business application(s)?
> I think I understand a little bit about it (from a conceptual
> perspective) that it's a self-healing 128 bit filesystem, better data
> integrity checking, etc.
> I have a small business (< 50 end users) and I'm wondering perhaps
> some examples that you might think would be most applicable for a
> FreeBSD server(s) and the ZFS filesystem
> One of the things that seems like might be a detriment as well as an
> asset, is it's ability to expand as necessary, but then I'm wondering
> what prevents the filesystem from just "running away"?

You can set a quota for each filesystem that it won't grow beyond.   
You can also set reservations to ensure a given filesystem will get a  
certain amount of space, even if other filesystems grow.   With  
intelligent use of these features you don't have to worry much about  
"runaway" filesystems.

ZFS is very handy for situations where you have a large storage pool  
that you want to split up for different users and applications.  It's  
much more flexible than a rigid partitioning scheme; you can safely  
and quickly resize filesystems to best use the available space.

I've also found the compression feature to be quite effective on  
filesystems that store data that compresses well.  We have an NFS  
share that stores mainly text, and with the default lzjb compression  
I've seen 1.5:1 ratios with no detectable performance hit. (Reads  
actually got slightly *faster*, but that may have been a testing  
glitch.)  gzip compression achieved much higher compression ratios but  
started to affect performance. I expect even better results when we  
eventually deploy ZFS deduplication.

ZFS snapshots are handy for recovering deleted user files without  
having to restore from backup.

NB: We're currently running OpenSolaris on our fileservers but I'm  
going to look into switching to FreeBSD now that ZFS on FreeBSD is a  
bit more mature.  I've gotten kind of disenchanted with OpenSolaris's  
slow update cycle.

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