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Date:      Wed, 15 Jul 2015 22:20:52 +0200
From:      Willem Jan Withagen <wjw@digiware.nl>
To:        Mark Felder <feld@FreeBSD.org>, Sean Chittenden <seanc@groupon.com>, Adrian Gschwend <ml-ktk@netlabs.org>
Cc:        FreeBSD Filesystems <freebsd-fs@freebsd.org>
Subject:   Re: FreeBSD 10.1 Memory Exhaustion
Message-ID:  <55A6C0A4.1030300@digiware.nl>
In-Reply-To: <1436989410.1427298.324703241.421E814B@webmail.messagingengine.com>
References:  <CAB2_NwCngPqFH4q-YZk00RO_aVF9JraeSsVX3xS0z5EV3YGa1Q@mail.gmail.com> <55A3A800.5060904@denninger.net> <55A4D5B7.2030603@freebsd.org> <55A4E5AB.8060909@netlabs.org> <CACfj5vJvAz9StvjTrA1TzfS%2BMhi_qSrOc_qBNHr8qXbiAj81xw@mail.gmail.com> <1436989410.1427298.324703241.421E814B@webmail.messagingengine.com>

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On 15/07/2015 21:43, Mark Felder wrote:
> 
> 
> On Tue, Jul 14, 2015, at 10:10, Sean Chittenden wrote:
>> I think the reason this is not seen more often is because people
>> frequently
>> throw limits on the arc in /boot/loader.conf:
>>
>> vfs.zfs.arc_min="18G"
>> vfs.zfs.arc_max="149G"
>>
>> ZFS ARC *should* not require those settings, but does currently for mixed
>> workloads (i.e. databases) in order to be "stable".  By setting fixed
>> sizes
>> on the ARC, UMA and ARC are much more cooperative in that they have their
>> own memory regions to manage so this behavior is not seen as often.
>>
>> To be clear, however, it should not be necessary to set parameters like
>> these in /boot/loader.conf in order to obtain consistent operational
>> behavior.  I'd be curious to know if someone running 10.2 BETA without
>> patches is able to trigger this behavior or not.  There was work done
>> that
>> reported helped with this between 10.1 and now.  To what extent it
>> helped,
>> however, I don't have any advice yet.
>>
> 
> I was about to email "I have 12TB at home and 4GB of RAM with a very
> erratic workload and never run into any issues" and then I looked at
> /boot/loader.conf and saw vfs.zfs.arc_max="2G"
> 
> Now I'm too scared to turn it off... :-)

Same here.
Just a leftover of all the advise to limit arc in the past.
Just bit the bullit: installed BETA1, killed the settings and rebooted.
We'll see what comes of it.

--WjW





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