On Tuesday, September 5, 2017 at 3:12:44 AM UTC+3, michael.ja...@gmail.com wrote: > > I am attempting to design a power backup for the beaglebone to ensure > corruption does not occur when power is lost. I understand this can happen. > Apparently it has happened with this product. >
My experience shows that the ext4 file system with journaling enabled does occasionally become corrupt when pulling the plug, although I've tried to avoid writing to the eMMC (no read-only root, just redirected all disk-hoggers to tmpfs-s in RAM). Still, during first half of the year I've had 3-4 cases of file system corruption among a set of ~10 devices which get their plug pulled daily (they are powered by street lighting circuits which are off during daytime). The easiest software "fix" I've come up with so far is mandatory fsck (the file system checker) on boot. This requires adding "fsck.mode=force fsck.repair=yes" to the kernel command line in /boot/uEnv.txt. On my desk it revives the corrupt ext4 file system automatically. Definitely not ideal, but the probability of ending up with an non-booting system is reduced (can't give stats, been only running this for 2 months). > Q1. In the real world, how long does the beaglebone black take to shutdown? > For me, around 8 seconds with a recent Debian 8.6 or 9.1 from https://rcn-ee.net/ (some services, some networking). I've seen bad network configuration delay it by another 5-10 seconds. > Q2. Apparently the power button is held down for 8 seconds. Does this > shutdown period commence from the end of that 8 seconds? > Pressing and immediately releasing the power button will trigger a software-initiated shutdown. Holding the power button down will probably do a "hard" shutdown, i.e. power will be cut. > Q3. From the notes left to me, I'm assuming the continuous current > consumption to be 500mA at the 5V supply. Would anyone have an idea of what > that may be during the shutdown period. > You'd have to measure that. I doubt it'll be any different from normal operation, unless shutdown triggers some externally connected HW to consume more. -- Kind regards, Tarmo Kuuse -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/2a71fca0-cced-4ae4-a020-b0b926ff2ebb%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
