From owner-freebsd-geom@FreeBSD.ORG  Thu Aug 10 19:19:11 2006
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Date: Thu, 10 Aug 2006 14:19:09 -0500
From: Craig Boston <craig@xfoil.gank.org>
To: Eric Anderson <anderson@centtech.com>
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References: <20060808195202.GA1564@garage.freebsd.pl>
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Cc: freebsd-fs@FreeBSD.org, Pawel Jakub Dawidek <pjd@FreeBSD.org>,
	freebsd-geom@FreeBSD.org
Subject: Re: GJournal (hopefully) final patches.
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On Thu, Aug 10, 2006 at 02:07:21PM -0500, Eric Anderson wrote:
> The size of the journal is related to the write speed of the journeled 
> device and the journal swap time (default 10 seconds).

I was going to ask if that was theoretical max speed for the bus or physical
write speed, but it appears that this is not (yet?) the case:

sbin/geom/class/journal/geom_journal.c:

                if (jsize == -1) {
                        /*
                         * No journal size specified. 1GB should be safe
                         * default.
                         */
                        jsize = 1073741824ULL;
                }
                msize = g_get_mediasize(data);
                ssize = g_get_sectorsize(data);
                if (jsize + ssize >= msize) {
                        gctl_error(req, "Provider too small for journalling. "
                            "You can try smaller jsize (default is %jd).",
                            jsize);
                        return;
                }