Date: Sat, 26 Mar 2016 10:15:05 -0600 From: Ian Lepore <ian@freebsd.org> To: Nikolai Lifanov <lifanov@mail.lifanov.com>, freebsd-arm@freebsd.org Subject: Re: Official images without noatime Message-ID: <1459008905.1091.100.camel@freebsd.org> In-Reply-To: <4b23b28ffae59216b5dde8f28f665330@mail.lifanov.com> References: <mailman.41.1458993601.86944.freebsd-arm@freebsd.org> <4b23b28ffae59216b5dde8f28f665330@mail.lifanov.com>
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On Sat, 2016-03-26 at 08:32 -0400, Nikolai Lifanov wrote: > > > > Hi, > > agree, in fact I have noatime on / as well. Shall be the default. > > > > > > > > Cheers, > > > > > > --- > > Jos? P?rez > > > > El 2016-03-26 00:38, Bernd Walter escribi?: > > > /boot/msdos has noatime, but / hasn't. > > > Considering SD media I think using noatime per default is a good > > > idea to avoid increased riscs of data loss on power failures. > > > > Since we also default to SU-no-J, power failure can be quite bad > during, > say, installworld. > With / noatime, I had my RPI2 lose files like /usr/bin/cmp, /bin/ls, > and > /bin/cat during a power loss. > Since it's not even possible to cleanly shut down this platform, I'm > for > enabling noatime for / on > at least for RPI and RPI2 platforms. I'm not sure why you think SU-no-J has anything to do with power failure, but before it turns into some kind of mythology let me just remind people that journaling does not enhance the ability to recover a filesystem, it only makes it faster to do so (when it doesn't fail completely, which it does all too often as seen with the numerous reports, some recent, of "it was finally fixed when I reran fsck without using the journal"). To get that boot-time speedup in recovery it has to do more writing as it goes (writing metadata to the journal and then again to the live filesystem all the time). Given the slow speed of sdcard writes, that's a steep price to pay to save 2 or 3 seconds of boot time after a power fail. Again: journaling doesn't add reliability, it only speeds recovery. On tiny sdcard filesystems the speedup is hardly noticible. -- Ian
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