Date: Fri, 07 Dec 2012 16:09:43 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> To: CeDeROM <cederom@tlen.pl> Cc: freebsd-current@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: UFS2 and Journaling in 9.1-RC3 Message-ID: <50C206B7.5040800@quip.cz> In-Reply-To: <CAFYkXjkH-Bj5ee7Y1dgEKXQQpdGwVUe7J=WEiAmJsO7T_uHyqw@mail.gmail.com> References: <CAFYkXj=iv_MWhLC5YTfXGZA7RdLt3iEEjT_sDfPETCDf%2BK-KaQ@mail.gmail.com> <k9srm6$56d$1@ger.gmane.org> <CAFYkXjkH-Bj5ee7Y1dgEKXQQpdGwVUe7J=WEiAmJsO7T_uHyqw@mail.gmail.com>
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CeDeROM wrote: > On Fri, Dec 7, 2012 at 2:41 PM, Ivan Voras<ivoras@freebsd.org> wrote: >> It looks like you are confusing GEOM journalling (-J) and UFS-SU >> journalling (-j). They are very different, and today you probably want >> to use the latter. If you are installing 9.x from scratch, it will be >> enabled by default. If not, you can use newfs -j or tunefs -j to enable it. > > "When any other means fail, read the manual" heh :-) > > I am still a bit confused, even after reading [1], because there is no > explanation of difference between GJournal and SU / SU+J (which was > introduced in FreeBSD 9.0). I understand GJournal works below > filesystem level and I dont need to use fsck. SU/SU+J is part of the > UDF/UDF2 filesystem. I should not use SU and GJournal at the same > time. What are the advantages of SU/US+J? What is the advantage of > SU+J over SU? Should I use Gjournal or SU/SU+J? Any hints welcome! :-) > > If I have already created UFS2 with -J, I understand I can switch it > off, can I then simply turn of UFS+J (-j) with no data loss on > existing filesystem? > > Which solution is better for drives>1TB when I dont want to wait an > hour for fsck? In short - if you choose Gjournal with data and journal on the same disk, you will have about half write speed. If you choose SU+J, you will not be able to use UFS snapshot feature at this time (there is some bug and snapshots on SU+J is disabled) Other than that - SU+J is easier to Enable / Disable on existing partition but is not well testet - it is younger technology than Gjournal. Miroslav Lachman
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