gjournal panic 7.0-RC1

[Chris]

> I did some experimentation with gjournal a few weeks ago to determine
> how I might partition
> a new server, as well as how large to make my journals and where.  I did
> find that for the computers
> I have tested so far, a 1 gig (default size) journal seems to be
> sufficient, but half of that or less is
> asking for trouble and I could not find any workarounds to reduce the
> chances of panic when I
> was already stuck with a too-small journal I created a while ago.  I
> also found the -s parameter
> is vague in that it does not say what units it accepts (appears to be
> bytes) and I *could not* get it
> to make a journal inside a data partition any bigger than somewhere
> around 1.7 gigs.  Some values
> of -s seemed to wrap around to a smaller number, while other values gave
> errors about being too small
> (when they weren't) or invalid size.  The only way I could force a
> journal size 2G or larger was
> to make a separate partition for journal.  On the server I was setting
> up, I decided to make my
> (journaled) data partitions da0s1d,e,f and the journals da0s2d,e,f.
>
> I'm just getting this out there to the list because I don't have time to
> debug it further.

thanks for this info I have spent some 8 hours on this today and it
seems the documentation for this is somewhat lacking all information
required, the server is handling large 50meg files, I have an
identical server that hasnt beetouched by gjournal and even after I
had setup gjournal properly so no more errors I then found the write
speeds were pretty poor, with hd load very high in vmstat.  My initial
impressions of gjournal is complicated to setup, unstable and slow
write speeds however I have not given up yet and may play with it a
little more tommorow.  The errors that were appearing are these.

ad4: FAILURE - WRITE_DMA48 status=51<READY,DSC,ERROR>
error=10<NID_NOT_FOUND> LBA=662870719

This is not hd failure but occurs when the gjournal was enabled on the
initial newfs but has no actual journal location.  I stopped these
errors after the proper configuration but of course had that single
panic.

If the only advantage of journaling is to avoid slow fsck's then I may
decide I can live without it, the real attraction to me was been able
to use the much glamorised async which is what made me so shocked when
write speeds were low.

Chris