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When copying large files or testing writespeed with dd, the max writespeed I can get is about 12-15MB/s on drives using the NTFS filesystem. I tested multiple drives (all connected using SATA) which all got writespeeds of 100MB/s+ on Windows or when formatted with ext4, so it's not an alignment or drive issue.

top shows high cpu usage for the mount.ntfs process.

AMD dual core processor (2.2 GHz)
Kernel version: 3.5.0-23-generic
Ubuntu 12.04
ntfs-3g version: both 2012.1.15AR.1 (Ubuntu default version) and 2013.1.13AR.2

How can I fix the writespeed?

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Have you tried testing dd with raw drive access (on the drive or partition, doesn't matter)? Note that testing that way will destroy the filesystem and will lose any data on it. It will bypass the NTFS drivers entirely. –  Bob Jun 30 '13 at 17:17
Yep I just did, the result is 149MB/s. –  Zulakis Jun 30 '13 at 17:20
Just out of curiosity I have to ask if this drive is one of those 4k drives and if therefore your filesystem might be unaligned somehow?! –  Waxhead Jun 30 '13 at 18:05
try bonnie++ and what kernel are you using? uname -r –  cybernard Jun 30 '13 at 18:25
I believe that the free version of NTFS-3G is crippled so that it uses 4 KiB writes with no caching, causing extremely slow write performance on SSDs and USB drives. The company behind the driver suggests buying the commercial version for better performance. Apparently no-one cares enough to actually fix (and if necessary, fork) the open source version because this problem has been around for almost a decade, ever since NTFS-3G was first released. –  Tronic Mar 9 at 2:23

1 Answer 1

perhaps check here for ideas on what could be causing it. http://www.tuxera.com/community/ntfs-3g-faq/#slow

This sounds a bit like the 'old days' when file io was not using DMA by default. It's unlikely these days but is BIOS using IDE emulation for SATA drives? Because if it is emulating IDE then it may also be emulating non-DMA mode as well.

Another potential slow down is if ntfs file compression. Is compression enabled on the folder you are writing to? If it is, that will make any new files in that folder compressed as well.

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How can I test if it is using DMA? Apart from this, I have already tried out all the suggestions on the page. –  Zulakis Jul 1 '13 at 13:53
Uhm, from what I have read, DMA is only relevant for IDE drives? I am only using SATA drives. –  Zulakis Jul 1 '13 at 13:58
According to en.wikipedia.org/wiki/Serial_ATA#Transport_layer it sounds like DMA is the only option for SATA. Lets find out if his bios is using ide emulation –  BeowulfNode42 Jul 2 '13 at 3:11

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