Gjournal reporting 1/2 the speed of non journaled? What is the status of Gjournal?

[N. Harrington]

--- Eric Anderson <anderson at freebsd.org> wrote:

> On 08/16/07 20:02, N. Harrington wrote:
> >  With ZFS, I have not seen much new going on with
> > gjournal. I am curious what the status of gjournal
> and
> > if it will likely be included with 6.3 (whenever
> that
> > is due)
> > 
> >  Also, as of late, I have been using it with
> > 6.2-STABLE via the patches and I seem to be
> getting
> > 1/2 the transfer speeds compared to non journaled
> > disks. It seems like this is recent as previous
> tests
> > showed it as quite fast.
> 
> It would help if you included your gjournal
> configuration, file system 
> configuration (how it was newfs'ed), what kind of
> performance you saw, 
> and what you expected.

 I left it "vague" as I was trying it on 3 different
setups. Also, since whatever the speed was with UFS,
became 1/2 with journal. So were I started from, each
being different, does not matter or really help.

 I did a standard newfs  ( newfs /dev/da1s1e and newfs
/dev/da1s1d ) before the journaling. After I edited
the bsdlabel to have the 16 offset.

 I have seen that there is a newfs -J, however I am
uncertain of its usage (or what it does) if one is
using a separate (beginning) slice for the journal.

Per Pawel, it seems perhaps my test is flawed. However
I would swear that doing this test before, showed an
improvement, not decrease. Hence I wonder if there has
been some recent change in 6-STABLE such that it does
not integrate as well somehow.


> 
> >  Any suggestions on why this could be happening
> > greatly appreciated.
> > 
> >  tested via 
> >  dd if=/dev/zero of=./testfile bs=16 count=16384
> 
> A 16byte block size is, well, really not going to
> prove much.  Try a 1m 
> block size.

 If I were using larger files, perhaps. But I store
many smaller files, so this seems much more realistic.
 I will perhaps try some slightly larger sizes.

> >  On 2 different dual opteron systems with 8 gigs
> of
> > Ram running FreeBSD 6.2-STABLE amd64 (as of 4 days
> > ago)
> > 
> >  Regardless of the disk (I tested scsi and ata and
> one
> > on a raid controller) both times I converted it to
> > journal, the speed went in half. 
> 
> Half of what, down to what?

 Why does that matter? If its 1/2, why does it matter
what it is 1/2 of?
 
> >  With disks getting larger and larger, why is it
> > taking so long for a journaled filesystem to be
> > standard on BSD?
> 
> 
> Since we've had soft-updates for quite some time, it
> has reduced the 
> need for a journaled file system, however it is of
> course increasingly 
> important.  I suppose one has not happened yet
> because not enough 
> developers have had the spare time to implement one.
>  Besides, in 
> 7-RELEASE, you'll have zfs, so there will be an
> option for you.  You can 
> always submit patches for journaling for one of the
> existing file 
> systems if you'd like.

 That assumes that I am a developer with such skills.
People always saying, then submit a patch, assumes one
has the skills and time to do so. I, and most
companies, would rather pay to have someone who has
the specialized skills to do the job well. I, and my
company contribute money to BSD, as that is the
resource we have available. I have seem some people
solicit money requests to do enhancement work etc..
Usually with good results. It seems to me, more would
get done that way than always assuming anyone who
knows how to use freeBSD well and or post on the
mailing list, has the ability to also write code for
it.
 (my tiny rant)


 Be well.

  Nicole


> Eric
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