== sanity-flr test 50a: mirror extend/copy preserves sparseness ========================================================== 22:33:28 (1789439608)
 ** create striped file /mnt/lustre/d50a.sanity-flr/f50a.sanity-flr
 ** write 1st data chunk at 1M boundary
20+0 records in
20+0 records out
20480 bytes (20 kB, 20 KiB) copied, 0.0537068 s, 381 kB/s
 ** write 2nd data chunk at 2M boundary
20+0 records in
20+0 records out
20480 bytes (20 kB, 20 KiB) copied, 0.0337096 s, 608 kB/s
 ** create hole at the file end
 ** verify sparseness
    first data offset: 1044480
    hole at the end: 3500000
 ** extend the file with new mirror
 ** verify mirror #2 sparseness
    first data offset: 1044480
    hole at the end: 3500000
 ** copy mirror #2 to mirror #1
mirror copied successfully: 1 
 ** verify mirror #1 sparseness again
    first data offset: 1044480
    hole at the end: 3500000
 ** final consumed blocks: 104