linux - Raspberry Pi system crashes at file transfer -

i have external 1tb hard drive, , usb-connect pi's usb slot, , mount (the whole drive 1 partition):

sudo mount -t ntfs-3g -o rw,uid=pi,gid=pi /dev/sda1 /mnt/book/ , mount goes through fine.

when try copy large folder [using sftp] , has many files, of them 1 big contiguous file reaches 5 gb per file (it's virtual machine), pi's system crash @ 1gb of file transfer (some times less that), have disconnect power cable , reconnect again ... reason??

-- edit --

source: computer, destination: hard drive connected rpi

both rpi , computer connected wirelessly through wireless router.

p.s. i'm have raspbian installed on raspberry pi.

-- edit 2 --

those ssh logs in auth.log

tail -f /var/log/auth.log

raspberrypi sshd[2077]: accepted password pi 192.168.0.3 port 47018 ssh2 raspberrypi sshd[2077]: pam_unix(sshd:session): session opened user pi (uid=0) raspberrypi cron[2183]: pam_unix(cron:session): session opened user root (uid=0) raspberrypi cron[2183]: pam_unix(cron:session): session closed user root raspberrypi sshd[2191]: accepted password pi 192.168.0.3 port 47125 ssh2 raspberrypi sshd[2191]: pam_unix(sshd:session): session opened user pi (uid=0) raspberrypi sshd[2198]: subsystem request sftp user pi raspberrypi sudo:       pi : tty=pts/0 ; pwd=/home/pi ; user=root ; command=/bin/mount -t ntfs-3g -o rw,uid=pi,gid=pi /dev/sda1 /mnt/book/ raspberrypi sudo: pam_unix(sudo:session): session opened user root pi(uid=0) raspberrypi sudo: pam_unix(sudo:session): session closed user root 

and logs didn't change before , after failure !!!

on computer, took snapshot failure when happens:

it said sftp can still suffer potential issues related ascii/binary transmission modes. can try using "scp" instead of "sftp"