zfs, 1 gig of RAM and periodic weekly

[Paul Mather]

On Feb 27, 2012, at 11:10 PM, Eugene M. Zheganin wrote:

> Hi.
> 
> On 28.02.2012 01:02, Nenhum_de_Nos wrote:
>> regardless of the pool size ?
>> 
>> I was planning on making an atom board a file server for my home, and I have two options: soekris
>> net6501 2GB RAM and intel board powered by the 330 atom (says 2GB limited as well). My plans are
>> to use from 4 up to 8 disks, and they should be 2TB at least.
>> 
>> As its for home use, some p2p software and mostly music listening and sometimes movie streaming.
>> 
>> should 2GB be that bad, that I should drop it and use UFS instead ?
>> 
>> I may run any version of FreeBSD on it, was planning on 9-STABLE or 9.1.
>> 
> In the same time I have a couple of hosts successfully running zfs on 768 Megs and on 1 Gig of RAM. Both i386.
> And they aren't affected by the periodic weekly for some reason. And they are used only as fileservers.


Basically the same story here: I am using a FreeBSD/i386 system with 768 MB of RAM running RELENG_8 with 4 x 1 TB drives arranged as a RAIDZ1 vdev.  It is used as a Bacula server, backing up to the ZFS pool (with ZFS compression enabled).  It has been rock solid, and I've had no problems with any of the periodic jobs.

Here are the ZFS-related tunings I have in /boot/loader.conf:

vm.kmem_size="640M"
vm.kmem_size_max="640M"
vfs.zfs.arc_max="512M"
vfs.zfs.txg.timeout="5"


If you are planning on using P2P a lot, I had heard that large files fetched via Bittorrent can become very fragmented under ZFS (due to the COW nature of ZFS and the way Bittorrent fetches files), especially if the pool is very full, and so ZFS might not be the best thing to use if you are also planning on streaming these files, especially on modest hardware.  UFS might be preferable in these circumstances.

Cheers,

Paul.