dd failed on ikshackbox master

dd failed on ikshackbox master
while copying ubuntu.img on to /dev/sda2 below error has been reported.
"fl source ubuntu" is not doing successful boot.
I think we may have to re-format the /dev/sda and copy ubuntu.img on to it.
or we may have to change the usb drive, if this error re-occurs again after re-format.

root@ikshackbox master:~# fdisk -l /dev/sda

Disk /dev/sda: 16.0 GB, 16008609792 bytes
128 heads, 32 sectors/track, 7633 cylinders, total 31266816 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot Start End Blocks Id System
/dev/sda1 * 63 106494 53216 c W95 FAT32 (LBA)
/dev/sda2 106496 4095999 1994752 83 Linux
root@ikshackbox master:~# dd if=ubuntu.img of=/dev/sda2
[ 240.997352] usb 1-1.2: device descriptor read/all, error -110
[ 256.167129] usb 1-1.2: device descriptor read/64, error -110
[ 271.366963] usb 1-1.2: device descriptor read/64, error -110
[ 276.586853] usb 1-1.2: device descriptor read/8, error -110
[ 281.726785] usb 1-1.2: device descriptor read/8, error -110
[ 286.946742] usb 1-1.2: device descriptor read/8, error -110
[ 292.086683] usb 1-1.2: device descriptor read/8, error -110
[ 292.227345] end_request: I/O error, dev sda, sector 603112
[ 292.243885] Buffer I/O error on device sda2, logical block 57631
[ 292.261975] Buffer I/O error on device sda2, logical block 57632
[ 292.279975] Buffer I/O error on device sda2, logical block 57633
[ 292.297972] Buffer I/O error on device sda2, logical block 57634
[ 292.315967] Buffer I/O error on device sda2, logical block 57635
[ 292.333962] Buffer I/O error on device sda2, logical block 57636
[ 292.351958] Buffer I/O error on device sda2, logical block 57637
[ 292.369953] Buffer I/O error on device sda2, logical block 57638
[ 292.387948] Buffer I/O error on device sda2, logical block 57639
[ 292.405944] Buffer I/O error on device sda2, logical block 57640
dd: writing to `/dev/sda2': Input/output error
496617+0 records in
496616+0 records out
254267392 bytes (254 MB) copied, 229.385 s, 1.1 MB/s
root@ikshackbox master:~# [ 308.116561] usb 1-1.2: device descriptor read/64, error -110
[ 323.316393] usb 1-1.2: device descriptor read/64, error -110
[ 338.596225] usb 1-1.2: device descriptor read/64, error -110
[ 353.796064] usb 1-1.2: device descriptor read/64, error -110
[ 359.015958] usb 1-1.2: device descriptor read/8, error -110
[ 364.155905] usb 1-1.2: device descriptor read/8, error -110
[ 369.375850] usb 1-1.2: device descriptor read/8, error -110
[ 374.515781] usb 1-1.2: device descriptor read/8, error -110
[ 374.635855] hub 1-1:1.0: unable to enumerate USB device on port 2

root@ikshackbox master:~#
root@ikshackbox master:~#reboot
....
Unable to find boot script - BOOTSCRIPT
>fl source ubuntu
Running script from flash - ubuntu
....
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Begin: Running /scripts/local-premount ... done.
mount: mounting /dev/sda2 on /root failed: Invalid argument

BusyBox v1.18.5 (Ubuntu 1:1.18.5-1ubuntu4) built-in shell (ash)
Enter 'help' for a list of built-in commands.

(initramfs)

complete log can be found at

https://pastebin.linaro.org/1117/