First, I'd like to be very clear on an important distinction:
- Partitions are simply pointers to where filesystems begin and end. On modern disks, these start and end points are expressed as sector values.
- Filesystems are complex data structures that reside within partitions (or other containers). Typically, filesystems are defined relative to the start point of the containing partition.
/dev/sda2 used to begin at sector 40,962,048. You changed it so that it now begins at sector 80,078,848. Thus, the critical early parts of the filesystem now begin outside the partition. An analogy might be if you somehow moved the front cover of a reference book, sitting flat on a table, a centimeter or so down without moving any of the pages of the book. When you opened the book, you'd find that the table of contents was missing, along with the first chapter or two. Those pages would now be floating freely, extracted from the book. You'd therefore be unable to find anything in the book except by reading the whole thing -- and even then, parts of it would be missing.
Generally speaking, any partitioning operation that involves moving or resizing the start of a partition is best done using GParted, which knows the proper order of operations for moving and resizing partition and filesystem data structures to keep everything working properly. Even GParted is not without its risks when resizing partitions, though -- especially not when the start point is involved, since this requires moving significant amounts of data, so a bug, power failure, hardware fault, or other problem can end up trashing the whole partition. If you must do it without GParted, you can, but you have to fully understand the distinction between a partition and a filesystem that I've outlined, and understand the implications of this distinction for the order in which you perform various operations (resize filesystem, move filesystem, change partition boundaries).
In your specific case, what I recommend is:
- Delete your new
- Re-create your
/dev/sda2 using its original start and end sector values. Be sure these are exactly the same as they were before.
- Check that the re-created
/dev/sda2 is accessible.
- Back up your important data from
- Re-evaluate whether you really need to move the start of the partition. I don't know what your ultimate goal is, so I can't do this for you. Perhaps moving the end point would work as well (and that would be safer); or maybe adding another disk would be a better option; or maybe you don't really need to repartition at all.
- If you must repartition the disk, use GParted to do the job.