On Wed, Feb 19, 2014 at 11:10:41AM -0500, Austin S Hemmelgarn wrote: > Currently, btrfs balance start fails when trying to convert metadata or > system chunks to dup profile on filesystems with multiple devices. This > requires that a conversion from a multi-device filesystem to a single > device filesystem use the following methodology: > 1. btrfs balance start -dconvert=single -mconvert=single \ > -sconvert=single -f / > 2. btrfs device delete / /dev/sdx > 3. btrfs balance start -mconvert=dup -sconvert=dup / > This results in a period of time (possibly very long if the devices are > big) where you don't have the protection guarantees of multiple copies > of metadata chunks. > > After applying this patch, one can instead use the following methodology > for conversion from a multi-device filesystem to a single device > filesystem: > 1. btrfs balance start -dconvert=single -mconvert=dup \ > -sconvert=dup -f / > 2. btrfs device delete / /dev/sdx > This greatly reduces the chances of the operation causing data loss due > to a read error during the device delete. > > Signed-off-by: Austin S. Hemmelgarn <ahferro...@gmail.com> Reviewed-by: David Sterba <dste...@suse.cz>
Sounds useful. The muliple devices + DUP is allowed setup when the device is added, this patch only adds the 'delete' counterpart. The imroved data loss protection during the process is a good thing. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
