Date: Tue, 28 Oct 2014 12:52:53 -0700 From: Kevin Oberman <rkoberman@gmail.com> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-stable <freebsd-stable@freebsd.org>, Chris H <bsd-lists@bsdforge.com> Subject: Re: Dump time issues Message-ID: <CAN6yY1v83YriMX%2B=mi6%2B%2Bu7NEvuNB3PFDHv%2BgohT7xNpF3fmcg@mail.gmail.com> In-Reply-To: <CAJ-Vmo=ahsmVPAmidB33NTtKmxv0QDvp%2BU4Mua3=z1bjQ4dC0w@mail.gmail.com> References: <6978A7BF-3CB7-4088-904D-5A60D755A04C@gmail.com> <20141025113846.GY1235@albert.catwhisker.org> <CAN6yY1tp%2Box6jHVnFJ4m3AYf4bBY-OzEfTnwrBHZZ0wwEARAxg@mail.gmail.com> <6bb4cda435fb420fb663fa1d47b85a08@ultimatedns.net> <CAN6yY1sOothUj1i5tTKPHDYNZ%2BCQ3ZKxmYrmq_GE4Ft66LPcBw@mail.gmail.com> <CAJ-Vmo=ahsmVPAmidB33NTtKmxv0QDvp%2BU4Mua3=z1bjQ4dC0w@mail.gmail.com>
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On Tue, Oct 28, 2014 at 12:20 PM, Adrian Chadd <adrian@freebsd.org> wrote: > On 27 October 2014 11:09, Kevin Oberman <rkoberman@gmail.com> wrote: > > >> I'm aware of two issues with SU+J, one of which is annoying and the > other > > is worse. > > 1. If the journal is not fully written on power fail or some other > reason, > > you may need to do a full fsck of the volume and the behavior of the > system > > until this is done can be very unpredictable. > > 2. You can't safely snapshot the system. This is what 'dump -L' does. > This > > means that some files dumped from a live FS may not be consistent (not > > good!) or, if '-L' is used, the system may well hang. > > > > While I love the fast fsck times (2 or 3 seconds) after a crash, I also > > question the default. Still, it may be a preferred choice be used for > very > > large file systems where a full fsck would take a very long time as long > as > > the risks are understood. For these systems, ZFS might be a better > choice. > > These arguments do NOT favor it being the default, IMHO. > > If people can reproduce SU+J problems then please file bugs. There > have been some fixes with the journal handling over the last year or > so and I haven't had this problem on -HEAD any longer, but it doesn't > mean it's there. > > > > > -adrian > The snapshot issue has been submitted to bugzilla several times. One is 173301. If it has been fixed, great, but the bug has not been touched and I have not seen any reports of it being fixed. Guess I could try a "dump -L" on my server and see, but I would hate to see it down for very long if the problem has not been fixed in 10.1-RC3-p1. Ihave no system running HEAD ATM, so If any fix has not made it to 10.1, I will not be able to test. The first issue is probably not a bug, but just very unlucky timing and does not damage the file system.I have seen many reports with the standard answer of "run a full fsck" which seems to fix it.
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