slow ZFS on FreeBSD 8.1

Freek van Hemert fvhemert at
Tue Jan 4 16:50:23 UTC 2011

Thank you mailinglist,

That was a lot of info. First of all, I don't think this is a cpu issue
since the cpu is mostly idle while copying.
Second, I tried the hacks in loader.conf and the other ones mentioned in the
beginning of the thread. Allthough perfomance is somewhat increased, it is
still horribly slow at something like 2.6MB/sec (my internet is faster.)

For the moment I will put my FreeBSD plans back in the fridge, I thought ZFS
would bring me instant performance and data safety without having to spend
too much time. I'll move back to Arch Linux and just setup a rsync between
the disks on ext4 or perhaps later I will move to btrfs. When 8,2 is stable
who knows I might just switch again although as the disks fill it will be
harder and harder...

I will definitely revisit FreeBSD and zfs but this was not the time for me.
Have a happy new year and thanks for all the comments.


On 2 January 2011 12:33, Dan Langille <dan at> wrote:

> On 12/31/2010 6:47 PM, Jeremy Chadwick wrote:
>> On Sat, Jan 01, 2011 at 10:33:43AM +1100, Peter Jeremy wrote:
>  Based on my experiences at home, I converted my desktop at work to
>>> pure ZFS.  The only issues I've run into have been programs that
>>> extensively use mmap(2) - which is a known issue with ZFS.
>> Is your ZFS root filesystem associated with a pool that's mirrored or
>> using raidzX?  What about mismatched /boot content (ZFS vs. UFS)?  What
>> about booting into single-user mode?
>> indirectly hints at these problems but
>> doesn't outright admit them (yet should), so I'm curious to know how
>> people have solved them.  Remembering manual "one-offs" for a system
>> configured this way is not acceptable (read: highly prone to
>> error/mistake).  Is it worth the risk?  Most administrators don't have
>> the tolerance for stuff like that in the middle of a system upgrade or
>> what not; they should be able to follow exactly what's in the handbook,
>> to a tee.
>> There's a link to at the bottom of the above Wiki page
>> that outlines "the madness" that's required to configure the setup, all
>> of which has to be done by hand.  I don't know many administrators who
>> are going to tolerate this when deploying numerous machines, especially
>> when compounded by the complexities mentioned above.
> This basically outlines the reason why I do not use ZFS on root.
> --
> Dan Langille -
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