cosmos72
Can I convert 33T logical partitions?
The ext4 logical partition made of three hard disks, the data is about 20T, and the conversion to xfs is wrong. How to solve this problem?
10:04:13 dd: Unable to target output file”/tmp/fstransform.mount.120513/.fstransform.loop.120513 35994497712127 Truncate at byte: file is too large
Short answer: an ext4 33TB filesystem is currently too large for conversion with fstransform; the current limit on ext4 is 16 TB.
Long answer: fstransform creates inside the filesystem to be converted a single sparse file as large as the filesystem itself, then formats the sparse file (to xfs, in this case), loop-mounts it and progressively moves data from the ext4 filesystem into the loop-mounted xfs sparse file.
Unluckily, ext4 maximum file size is 16 TB - see https://en.wikipedia.org/wiki/Ext4 - thus the error you reported.
A possible, future, solution could be to create several smaller files, and view them as a single block device using Linux Device Mapper instead of the current solution that uses loop devices. This would require modifying fstransform, clearly.
