Re: Yanking a USB Hard Drive/ReiserFS causes Kernel Panic
John L Fjellstad wrote:
William Ballard <email@example.com> writes:
I have an external USB 2.0 2.5" hard drive, shows up as /dev/sda, with
an ReiserFS partition. If I yank it with it mounted ReiserJS panics.
I have the fstab entry marked as sync, rw.
I think it might be because reiserfs is a journaling filesystem. I know
I sometimes forget and remove my usbkey (which has FAT) without
unmounting, and don't see the problems you see. Even ext2 should be
Absolutely not. The point of keeping a journal is to preserve the
integrity of the filesystem even in an operation is unexpectedly
interrupted (whether by a crash or a power failure). This should
provide resilience to disconnection, too, but that doesn't mean
disconnection without warning would be safe: the integrity of the
filesystem is not the same as the integrity of every file within it.
If an ext2 filesystem is not cleanly unmounted then there is no
guarantee that it will be consistent or quickly repairable. It must
generally be fully scanned and repaired by e2fsck. If the filesystem is
not mounted with metadata ordering enabled, even that won't necessarily
FAT isn't resilient to interruption either. FAT filesystem
implementations tend to be extremely conservative in ordering of
changes, which may make it relatively safe to disconnect a FAT
filesystem without unmounting it. However, there's no way of telling
whether a FAT filesystem has been cleanly umounted or not, so filesystem
damage can easily go unnoticed for some time, giving a false sense of
the safety of this practice.