On Mon, Mar 5, 2018 at 6:38 PM, Curtis Maurand <cmaur...@xyonet.com> wrote:

> ZFS is a memory hog.   you need 1 GB of RAM for each TB of disk.


Curtis, can you provide some more details? I have been testing this for the
last couple of weeks and ZFS doesn't require 1G for each TB to function
(which is the standard meaning of need).
>From my direct testing and experience 1G per TB is a rule of thumb for
suggested memory sizing on general purpose servers. Do you have specific
information that violating this rule of thumb will cause functional issues?

To be more blunt, was this a case of drive by nerd sniping or do you know
something that will cause my specific use case to fail at some point in the
future?


Walter



> On 3/1/2018 1:49 AM, Walter Parker wrote:
>
>> Forgot to CC the list.
>>
>> On Wed, Feb 28, 2018 at 10:13 PM, Walter Parker <walt...@gmail.com>
>> wrote:
>>
>> Thank you for the backup script.
>>>
>>> By my calculations, 2G should be enough. If I limit the ARC cache to 1G,
>>> that leaves 1G for applications & kernel memory. As I'm not serving the
>>> 6TB
>>> drive up as a file server, but using it for one specific task (to receive
>>> the backups from one host) I figure that I don't need lots of memory. ZFS
>>> as a quick file server or busy server needs lots of memory to be quick.
>>> I've seen testing showing ZFS doing fast file copies on as little as 768M
>>> total system after proper memory tuning.
>>>
>>> I need ZFS because it is the only file system that can receive
>>> incremental
>>> ZFS snapshots and apply them. I have not setup the ZFS backup software
>>> yes,
>>> so I'm just using rsnapshot. First time it ran, it filled all 1G of the
>>> cache. I rebooted the firewall afterwards and now ZFS with 60-100M of
>>> usage
>>> (the amount of data that rsync updates on a daily basis is pretty small).
>>> Right now, the data from the other server is ~8.8G, compressed to 1.7G
>>> with
>>> lz4.
>>>
>>> When I get the full backup running, I will be ~1.5TB in size. ZFS
>>> snapshots should be pretty small and quick (as it can send just the data
>>> that was updated without having to walk the entire filesystem). An rsync
>>> backup would have to walk the whole system to find all of the changes.
>>> Most
>>> of the data on the system doesn't change (as it is a media library).
>>>
>>> I'll post back more results if people are interested, after I get the
>>> backup software working (I'm thinking about using ZapZend).
>>>
>>>
>>> Walter
>>>
>>>
>>>
>>> On Wed, Feb 28, 2018 at 8:54 PM, ED Fochler <soek...@liquidbinary.com>
>>> wrote:
>>>
>>> I feel like I'm late in responding to this, but I have to say that 2GB of
>>>> RAM doesn't seem like nearly enough for a 6TB zfs volume.  ZFS is great
>>>> in
>>>> a lot of ways, but is a RAM consuming monster.  For something RAM
>>>> limited
>>>> like the 2220 I'd use a different, simpler file format.  Then I'd use
>>>> rsync
>>>> based snapshots.
>>>>
>>>> Here's my personal backup script.  :-)  I haven't tried it FROM pfsense,
>>>> but I've used it to back up pfsense.
>>>>
>>>>          ED.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On 2018, Feb 21, at 12:23 PM, Walter Parker <walt...@gmail.com> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> I have 2.4.2 installed on an SG-2220 from Netgate [nice box]. I just
>>>>>
>>>> bought
>>>>
>>>>> a 6TB powered USB drive from Costco and it works great (the drive has
>>>>>
>>>> its
>>>>
>>>>> own power supply and a USB hub). I want to use it take ZFS backups from
>>>>>
>>>> my
>>>>
>>>>> home server.
>>>>>
>>>>> I edited /boot/loader.conf.local and /etc/rc.conf.local to load ZFS on
>>>>>
>>>> boot
>>>>
>>>>> and created a pool and a file system. That worked, but the memory ran
>>>>>
>>>> low
>>>>
>>>>> so I restricted the ARC cache to 1G to keep a bit more memory free and
>>>>> rebooted. When the system rebooted it did not remount the pool (and
>>>>> therefore the file system) because the pool what marked as in use by
>>>>> another system (itself). That means that the pool was not properly
>>>>> exported/umounted at shutdown.
>>>>>
>>>>> Taking a quick look a rc.shutdown, I notice that it calls a customized
>>>>> pfsense shutdown script at the beginning and then exits. Is there a
>>>>> good
>>>>> place in the configuration where I can put/call the proper zfs shutdown
>>>>> script so that the pool is properly stopped/exported so that it imports
>>>>> correctly on boot?
>>>>>
>>>>>
>>>>> Walter
>>>>>
>>>>> --
>>>>> The greatest dangers to liberty lurk in insidious encroachment by men
>>>>> of
>>>>> zeal, well-meaning but without understanding.   -- Justice Louis D.
>>>>>
>>>> Brandeis
>>>>
>>>>> _______________________________________________
>>>>> pfSense mailing list
>>>>> https://lists.pfsense.org/mailman/listinfo/list
>>>>> Support the project with Gold! https://pfsense.org/gold
>>>>>
>>>>
>>>>
>>>>
>>> --
>>> The greatest dangers to liberty lurk in insidious encroachment by men of
>>> zeal, well-meaning but without understanding.   -- Justice Louis D.
>>> Brandeis
>>>
>>>
>>
>>
> --
> Best Regards
> Curtis Maurand
> Principal
> Xyonet Web Hosting
> mailto:cmaur...@xyonet.com
> http://www.xyonet.com
>
> _______________________________________________
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>



-- 
The greatest dangers to liberty lurk in insidious encroachment by men of
zeal, well-meaning but without understanding.   -- Justice Louis D. Brandeis
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