Very Slow file transfer between Linux and External Western Digital USB Hardisk

Errors and Solutions #27

Symptom:

While making backup from Linux to external HD, the transfer rate decreases dramatically until it reaches 1MB/s and then it hangs (most of the time)

Context:
External Western Digital HD
USB 2.0 connection
XX GBs of files
Linux 11.10
Tried both filesystems (EXT4 and NTFS ) on the External hard disk


Solution:

After hours of investigations, it seems that this is related to a change in Hard Disks technology which requires special partitioning steps

Previously the default sector size was 512 byte while now most of the new HDs uses 4096 byte sector, thus if the HD was not partitioned correctly ( properly aligned ) performance will degrade because of sector translation overhead and other technical issues ...

After applying the below changes i managed to copy large files on a consistent 20-30 MB/s transfer rate

How to align/repartition your HD

https://www.ultimateeditionoz.com/forum/viewtopic.php?f=94&t=1266
http://www.networkedmediatank.com/printthread.php?tid=46055 (video included)


More information about 4096 byte sector

http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/index.html?ca=dgr-lnxw074KB-Disksdth-LX

http://en.wikipedia.org/wiki/Advanced_Format#Advanced_Format_overview

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