On Mon, Oct 24, 2016 at 03:35:06PM +0200, Gandalf Corvotempesta wrote:> 2016-10-24 11:29 GMT+02:00 Niels de Vos <ndevos at redhat.com>: > > The filesystem on the brick will detect the problem, and most likely > > aborts itself. Depending on the configuration (mount options, tune2fs) > > the kernel will panic or mount the filesystem in read-only mode. > > > > When the filesystem becomes read-only, the brick process will log a > > warning and exit. > > So, gluster is able to handle a single bad sector. Kernel puts the FS > in readonly and the brick process will exit. > When the brick process exist, gluster detect the brick as missing and > so on........Yes, correct. But note that different filesystems can handle bad sectors differently, read-only filesystems is the most common default though. In 'man 8 mount' the option "errors=" describes the different values for ext2/3/4. Configuring it to "continue" will most likely cause data corruption or other bad problems and is definitely not advised ;-) Niels -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: not available URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20161024/e37bef5c/attachment.sig>
2016-10-24 16:13 GMT+02:00 Niels de Vos <ndevos at redhat.com>:> Yes, correct. But note that different filesystems can handle bad sectors > differently, read-only filesystems is the most common default though.Yes, I know. Anyway, even the first bit-rot scrub should detect the failed sector and trigger the error, right ?> In 'man 8 mount' the option "errors=" describes the different values for > ext2/3/4. Configuring it to "continue" will most likely cause data > corruption or other bad problems and is definitely not advised ;-)That's for sure :)
2016-10-24 16:13 GMT+02:00 Niels de Vos <ndevos at redhat.com>:> Yes, correct. But note that different filesystems can handle bad sectors > differently, read-only filesystems is the most common default though. > > In 'man 8 mount' the option "errors=" describes the different values for > ext2/3/4. Configuring it to "continue" will most likely cause data > corruption or other bad problems and is definitely not advised ;-)>From the opennebula forum:"I think your notion of kernel behaviour during disk failures is not correct. First of all, this is heavily filesystem dependent. Moreover, when the bad sector is in the file data (as opposed to filesystem metadata), read(2)returns something like ENXIO, and the filesystem continues operating. When the bad sector is in the filesystem metadata, most filesystems remount themselves read-only (AFAIK with ext*fs, the exact behaviour can be set via tune2fs(8) as "remount r/only", "panic", and "ignore" for the brave :-). When the disk is bad to the point of generating unplug/replug sequence (e.g. SATA channel reset), the filesystem starts returning ENXIO for all operations, but it is still mounted. For systemd-based distributions, systemd sometimes detects an unplugged disk (if it is mounted via /etc/fstab entry), and umount(2)s it. The kernel itself does not disable the disk, nor it remounts it r/only in response to all types of failure." so, how gluster handle a ENXIO ?