ZFS vs OSX Time Machine

[Jeremy Chadwick]

On Thu, Apr 28, 2011 at 05:27:04PM -0400, John Baldwin wrote:
> On Thursday, April 28, 2011 3:56:01 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?
> > > 
> > > 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..
> > > 
> > > 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..
> > > 
> > > 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 at midget.dons.net.au:/usr/obj/usr/src/sys/MIDGET  amd64
> > > 
> > > It is a 5 disk RAIDZ1 with 1.29Tb free using WD10EADS drives.
> > > 
> > > I don't see any SMART errors or ZFS warnings.
> > > 
> > > I have the following ZFS related tunables
> > > 
> > > vfs.zfs.arc_max="3072M"
> > > vfs.zfs.prefetch_disable="1" 
> > > vfs.zfs.txg.timeout=5
> > > vfs.zfs.cache_flush_disable=1
> > 
> > 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.
> 
> Huh?  I use values without quotes all the time in loader.conf.

I've seen cases where entries in /boot/loader.conf throw parser errors
during loader(8) when quotes aren't used.  The man page denotes that
quotes are required, which doesn't appear to be true?  Possibly the
parser only throws errors if non-numeric/non-integer values (e.g.
strings) are specified without quotes.

It's interesting that in the BUGS section of the man page the syntax
shown for hw.ata.ata_dma=0 also ""violates"" the ""required"" syntax.

So the question is: what's reality, and would better documentation
suffice?

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.               PGP 4BD6C0CB |