From: Jan Kara <jack@suse.cz>
To: Steve Kenton <skenton@ou.edu>
Cc: linux-fsdevel@vger.kernel.org, jack@suse.cz, pali.rohar@gmail.com
Subject: Re: Sync took ~8 hours to complete on a UDF DVD+RW with very complex directory structure
Date: Fri, 20 Jan 2017 13:23:02 +0100 [thread overview]
Message-ID: <20170120122302.GA18224@quack2.suse.cz> (raw)
In-Reply-To: <20170112003502.11233-1-skenton@ou.edu>
On Wed 11-01-17 18:35:02, Steve Kenton wrote:
> I first noticed this with 4.10rc2+ while testing some changes I was
> making to the UDF driver but it's neither a new problem nor related to my
> changes. Below is a test run on a stock Ubuntu 14.04 system with kernel
> 3.19 and the results are the same. If I copy large video files to the DVD
> I can put 4+GiB on the disk, it syncs as expected and life is good. If I
> try to copy Linus' 2.7GiB repo to the DVD it is still going after running
> overnight and after killing the copy sync does not return for hours,
> which hangs a graceful reboot. I should note that while the sync has not
> completed the filesystem on the DVD seems usable for the light testing I
> did using df, ls, find etc and the verbose copy was still proceeding if
> slowly when I killed it.
Yeah, I think the problem is that seeking just kills the DVD drive and UDF
driver in Linux is not very good in avoiding them. So writing to a UDF
filesystem on DVD media directly simply does not work very well. Also if
you copy a directory tree, there are lots of inplace updates of directories
happening so that may contribute to slowness as well. So all in all I don't
think this was ever something we were trying to make work reasonably since
people don't tend to use DVD like this...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2017-01-20 12:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-12 0:35 Sync took ~8 hours to complete on a UDF DVD+RW with very complex directory structure Steve Kenton
2017-01-20 12:23 ` Jan Kara [this message]
2017-01-20 15:27 ` Steve Kenton
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