Some comments on ZFS

Thomas Sparrevohn Thomas.Sparrevohn at
Tue Apr 17 20:37:14 UTC 2007

On Tuesday 17 April 2007 12:43:13 Gary Jennejohn wrote:
> Robert Watson writes:
> Interestingly enough, I see less memory pressure since switching to ZFS.
> But I'm not using RAIDZ. Previously ``make buildworld'' would use much
> more memory, probably for buffer caching. It looks like ZFS doesn't use
> nearly as much buffer cache as UFS (which may not be a good thing).

On this system 4GB system - 2,3GB available - ZFS stops around
1,3GB Free whereas UFS continues until app. 700MB mark on a

But the price seems to be much more disk activity - Given that
the difference - after disabling Witness - was  

UFS 10m32.10s real          27m1.32s user           7m49.01s sys     (Systat 700MB Free)
ZFS  17m43.66s real          27m30.70s user          17m28.47s sys  (Systat 1,3GB Free)

It make me think that ZFS is trading memory for performance - my guess is -
that given the same memory usage ZFS would be unbeatable - I must
say that Pawel has done a great job porting ZFS 

> ---
> Gary Jennejohn / garyjATjennejohnDOTorg gjATfreebsdDOTorg garyjATdenxDOTde
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