Date: Thu, 28 Apr 2011 16:53:03 -0400 From: Scott Sipe <cscotts@gmail.com> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-stable List <freebsd-stable@freebsd.org> Subject: Re: ZFS vs OSX Time Machine Message-ID: <AEF911FC-7AAE-4AEA-82C8-FEBC8D23B819@gmail.com> In-Reply-To: <20110428195601.GA31807@icarus.home.lan> References: <537A8F4F-A302-40F9-92DF-403388D99B4B@gsoft.com.au> <20110428195601.GA31807@icarus.home.lan>
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On Apr 28, 2011, at 3:56 PM, Jeremy Chadwick wrote: > On Thu, Apr 28, 2011 at 11:33:22PM +0930, Daniel O'Connor wrote: >> Does anyone else use ZFS to store TM backups? >>=20 >> I find that whenever my laptop (over wifi!) starts a TM the ZFS = machine it's backing up to grinds to a halt.. Other systems streaming = stuff over NFS from it also tend to stall.. >>=20 >> I presume that TM is doing something which causes ZFS some issues but = I'm not sure how to find out what the real problem is let alone how to = fix it.. >>=20 >> I am running FreeBSD midget.dons.net.au 8.2-PRERELEASE FreeBSD = 8.2-PRERELEASE #8 r217094M: Sat Jan 8 11:15:07 CST 2011 = darius@midget.dons.net.au:/usr/obj/usr/src/sys/MIDGET amd64 >>=20 >> It is a 5 disk RAIDZ1 with 1.29Tb free using WD10EADS drives. >>=20 >> I don't see any SMART errors or ZFS warnings. >>=20 >> I have the following ZFS related tunables >>=20 >> vfs.zfs.arc_max=3D"3072M" >> vfs.zfs.prefetch_disable=3D"1"=20 >> vfs.zfs.txg.timeout=3D5 >> vfs.zfs.cache_flush_disable=3D1 >=20 > Are the last two actually *working* in /boot/loader.conf? Can you > verify by looking at them via sysctl? AFAIK they shouldn't work, = since > they lack double-quotes around the values. Parsing errors are = supposed > to throw you back to the loader prompt. See loader.conf(5) for the > syntax. In my /boot/loader.conf I have: vfs.zfs.arc_max=3D6200000000 vfs.zfs.vdev.min_pending=3D4 vfs.zfs.vdev.max_pending=3D8 vfs.zfs.txg.timeout=3D5 vfs.zfs.prefetch_disable=3D1 And they all are properly reflected in sysctl values (no parse errors = seen). > Next, you COULD try using Samba/CIFS on the FreeBSD box to see if you > can narrow the issue down to bad NFS performance. Please see this = post > of mine about tuning Samba on FreeBSD (backed by ZFS) to get extremely > good performance. Many people responded and said their performance > drastically improved (you can see the thread yourself). The trick is > AIO. You can ignore the part about setting vm.kmem_size in = loader.conf; > that advice is now old/deprecated (does not pertain to you given the > date of your kernel), and vfs.zfs.txg.write_limit_override is = something > you shouldn't mess with unless absolutely needed to leave it default: >=20 > = http://lists.freebsd.org/pipermail/freebsd-stable/2011-February/061642.htm= l Just wanted to note that we were having a terrible time with ZFS = performance. Copying just a single large file over the network would = bring interactive system usage to an absolute crawl (system is 2x xeons, = 12gb ram). Thanks to your optimizations we have great ZFS + Samba = performance. We also use Netatalk for afpd file sharing (though I have = not tried Netatalk as a Time Machine target) and our performance is = quite good there as well. Scott
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