Cause of I/O error with dd after 10GiB using split?

Quote:

# dd if=/dev/sda3 bs=2M | split -b 3758096K - /mnt/sdc2/DELL-BACKUP/OS.img.part- dd: error reading '/dev/sda3': Input/output error 5164+1 records in 5164+1 records out 10831069184 bytes (11 GB, 10 GiB) copied, 383.179 s, 28.3 MB/s #

This is my 4th attempt in two 32-bit Ubuntu-based os. Block size was varied. File system is NTFS:

sda3 218.2 GB (primary Windows 7 partition)
sda2 14.7 GB recovery
sda1 39.2 MB system

system & recovery are successfully archived.