From: Dave Chinner <david@fromorbit.com>
To: Martin Steigerwald <martin@lichtvoll.de>
Cc: "Richard W.M. Jones" <rjones@redhat.com>, linux-xfs@vger.kernel.org
Subject: Re: mkfs.xfs options suitable for creating absurdly large XFS filesystems?
Date: Wed, 5 Sep 2018 08:23:45 +1000 [thread overview]
Message-ID: <20180904222345.GV5631@dastard> (raw)
In-Reply-To: <8045369.1GWcTSHGau@merkaba>
On Tue, Sep 04, 2018 at 05:36:43PM +0200, Martin Steigerwald wrote:
> Dave Chinner - 04.09.18, 02:49:
> > On Mon, Sep 03, 2018 at 11:49:19PM +0100, Richard W.M. Jones wrote:
> > > [This is silly and has no real purpose except to explore the limits.
> > > If that offends you, don't read the rest of this email.]
> >
> > We do this quite frequently ourselves, even if it is just to remind
> > ourselves how long it takes to wait for millions of IOs to be done.
>
> Just for the fun of it during an Linux Performance analysis & tuning
> course I held I created a 1 EiB XFS filesystem a sparse file on another
> XFS filesystem on an SSD of a ThinkPad T520. It took several hours to
> create, but then it was there and mountable. AFAIR the sparse file was a
> bit less than 20 GiB.
Yup, 20GB of single sector IOs takes a long time.
> Trying to write more data to it than the parent filesystem can hold back
> then resulted in "lost buffer writes" or something like that in
> kernel.log, but no visible error message to the process that wrote the
> data.
That should mostly be fixed by now with all the error handling work
that went into the generic writeback path a few kernel releases ago.
Also, remember that the only guaranteed way to determine that there
was a writeback error is to run fsync on the file, and most
applications don't do that after writing their data.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2018-09-05 2:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-03 22:49 mkfs.xfs options suitable for creating absurdly large XFS filesystems? Richard W.M. Jones
2018-09-04 0:49 ` Dave Chinner
2018-09-04 8:23 ` Dave Chinner
2018-09-04 9:12 ` Dave Chinner
2018-09-04 8:26 ` Richard W.M. Jones
2018-09-04 9:11 ` Dave Chinner
2018-09-04 9:45 ` Richard W.M. Jones
2018-09-04 15:36 ` Martin Steigerwald
2018-09-04 22:23 ` Dave Chinner [this message]
2018-09-05 7:09 ` Martin Steigerwald
2018-09-05 7:43 ` Dave Chinner
2018-09-05 9:05 ` Richard W.M. Jones
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