On 2016-09-12 10:51, Chris Murphy wrote:
On Mon, Sep 12, 2016 at 8:09 AM, Henk Slager <eye...@gmail.com> wrote:
FWIW, I use BTRFS for /boot, but it's not for snapshotting or even the COW,
it's for DUP mode and the error recovery it provides. Most people don't
think about this if it hasn't happened to them, but if you get a bad read
from /boot when loading the kernel or initrd, it can essentially nuke your
whole system. I run BTRFS for /boot in DUP mode with mixed-bg (because I
only use 512MB for boot) to mitigate the chance that a failed read has any
impact, and ensure that if it does, it will refuse to boot instead of
booting with a corrupted kernel or initrd.
Suppose kernel and initrd are on a BTRFS fs with data, metadata and
system all single profile. Will a bootloader then just continue
booting up a system even when there are csum errors in kernel and/or
initrd files? Suppose the bootloader is grub2.
I"m wondering the same thing. I don't know if GRUB's Btrfs code checks
for csum matches, and on error whether it knows to retry from some
other block group.
I can test this and report results (I've got GRUB built with the FUSE
based mount tool, which lets you use GRUB's FS modules from regular
Linux userspace), but it may be a while before I can get things set up
to properly test it.
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