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Date:      Wed, 27 May 2015 16:10:50 -0500
From:      Brandon Wandersee <brandon.wandersee@zoho.com>
To:        freebsd-questions@freebsd.org
Subject:   Re: ZFS in a VM?
Message-ID:  <20150527211050.GA11054@WorkBox.Home>
In-Reply-To: <CD14530C-58EB-4DA4-8DA0-59B3A1711A05@shire.net>
References:  <CA+sg5RQgF7+AQu9P0Bt8USF8722QCi=qJ2XQ8RbNQ92cv9tNTg@mail.gmail.com> <9C96EB4B-A230-4A26-BDC3-067367A61E34@shire.net> <CA+sg5RR29vXowwyhOPOXmNU0ex9XW0fVui2fB1sgdsDPCKZUkg@mail.gmail.com> <CD14530C-58EB-4DA4-8DA0-59B3A1711A05@shire.net>

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On 05/27, Chad Leigh Shire.Net LLC wrote:
> 
> > On May 27, 2015, at 1:41 PM, Jaime Kikpole <jkikpole@cairodurham.org> wrote:
> > 
> > On Wed, May 27, 2015 at 3:39 PM, Chad Leigh Shire.Net LLC
> > <chad@shire.net> wrote:
> >> I do.  I do it not so much for any performance benefits, if any, ZFS offers, but more for data integrity.
> > 
> > Exactly what I was looking for, too.
> > 
> > 
> >> You need to tune it since the VM based disks are not the same as physical disks.
> > 
> > I'm afraid that I don't understand.  Can you explain what you mean by "tune it?"
> 
> There are various kernel “tunables” (aka “kernel state”, settable “variables” in the kernel, see “man sysctl”) that affect ZFS.  
 
A lot of tuning "knobs" are described here:

http://www.solarisinternals.com/wiki/index.php/ZFS%5FEvil%5FTuning%5FGuide

As others have implied/stated, any results you get from a VM (especially after
fiddling with tuning) won't accurately reflect anything you'd get from using ZFS
on bare metal, and some operations are just out of the question.


-- 
===========================================
        :: Brandon Wandersee ::
    :: brandon.wandersee@zoho.com ::
===========================================
"A common mistake that people make when
trying to design something completely
foolproof is to underestimate the ingenuity
of complete fools."
                            - Douglas Adams
===========================================




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