Date: Mon, 1 Jul 2013 14:04:24 -0400 From: Scott Sipe <cscotts@gmail.com> To: Jeremy Chadwick <jdc@koitsu.org> Cc: freebsd-stable List <freebsd-stable@freebsd.org>, Paul Mather <pmather@vt.edu> Subject: Re: ZFS Panic after freebsd-update Message-ID: <CA%2B30O_PYPAWFwYoQo7AOC3Y5dGcPzYk65qrXxgZ4nJfH6i4Kvw@mail.gmail.com> In-Reply-To: <20130701170422.GA65858@icarus.home.lan> References: <CA%2B30O_P7=3FanLaxjHQ71grqWLfTxNJXb6kP5-eWYWEYZFoVtw@mail.gmail.com> <20130701154925.GA64899@icarus.home.lan> <C13462A8-88DC-4EEF-9356-CF655B8EA8E8@vt.edu> <20130701170422.GA65858@icarus.home.lan>
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On Mon, Jul 1, 2013 at 1:04 PM, Jeremy Chadwick <jdc@koitsu.org> wrote: > On Mon, Jul 01, 2013 at 12:23:45PM -0400, Paul Mather wrote: > > On Jul 1, 2013, at 11:49 AM, Jeremy Chadwick <jdc@koitsu.org> wrote: > > > > > Of course when I see lines like this: > > > > > > Trying to mount root from zfs:zroot > > > > > > ...this greatly diminishes any chances of "live debugging" on the > > > system. It amazes me how often I see this come up on the lists -- > people > > > who have ZFS problems but use ZFS for their root/var/tmp/usr. I wish > > > that behaviour would stop, as it makes debugging ZFS a serious PITA. > > > This comes up on the list almost constantly, sad panda. > > > > > > I'm not sure why it amazes you that people are making widespread use of > ZFS. > > It's not widespread use of ZFS. It's widespread use of ZFS as their > sole filesystem (specifically root/var/tmp/usr, or more specifically > just root/usr). People are operating with the belief that "ZFS just > works", when reality shows "it works until it doesn't". The mentality > seems to be "it's so rock solid it'll never break" along with "it can't > happen to me". I tend to err on the side of caution, hence avoidance of > ZFS for critical things like the aforementioned. > > It's different if you have a UFS root/var/tmp/usr and ZFS for everything > else. You then have a system you can boot/use without issue even if ZFS > is crapping the bed. > > ... > > 95% of FreeBSD users cannot debug kernel problems**. To debug a kernel > problem, you need: a crash dump, a usable system with the exact > kernel/world where the crash happened (i.e. you cannot crash 8.4 ZFS and > boot into 8.2 and reliably debug it using that), and (most important of > all) a developer who is familiar with kernel debugging *and* familiar > with the bits which are crashing. Those who say what you're quoting are > often the latter. > > ... > > But the OP is running -RELEASE, and chooses to run that, along with use > of freebsd-update for binary updates. Their choices are limited: stick > with 8.2, switch to stable/X, cease use of ZFS, or change OSes entirely. > So I realize that neither 8.2-RELEASE or 8.4-RELEASE are stable, but I ultimately wasn't sure where the right place to go for discuss 8.4 is? Beyond the FS mailing list, was there a better place for my question? I'll provide the other requested information (zfs outputs, etc) to wherever would be best. This is a production machine (has been since late 2010) and after tweaking some ZFS settings initially has been totally stable. I wasn't incredibly closely involved in the initial configuration, but I've done at least one binary freebsd-update previously. Before this computer I had always done source upgrades. ZFS (and the thought of a panic like the one I saw this weekend!) made me leery of doing that. We're a small business--we have this server, an offsite backup server, and a firewall box. I understand that issues like this are are going to happen when I don't have a dedicated testing box, I just like to try to minimize them and keep them to weekends! It sounds like my best bet might be to add a new UFS disk, do a clean install of 9.1 onto that disk, and then import my existing ZFS pool? Thanks, Scott
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