NTFS write speed really slow (<15MB/s) on Ubuntu

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?

Solution 1:

A previous post was on the right track with the reference provided:

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

The original question mentions noticing the issue with large file transfers. In my experience with copying media files or doing backups, the key option in the above FAQ was:

Workaround: using the mount option “big_writes” generally reduces the CPU usage, provided the software requesting the writes supports big blocks.

Simply add the big_writes option, e.g.

sudo mount -o big_writes /dev/<device> /media/<mount_dir>

My Linux NAS with a low spec CPU now manages NTFS large file writes about three times faster. It improved from ~17MB/s to 50MB/s+. Even seen it peek at about 90MB/s in iotop which is probably near the external drives capability (a 2.5" USB3 HDD).

From the NTFS-3G man page:

 big_writes
              This option prevents fuse from splitting write buffers  into  4K
              chunks,  enabling  big  write buffers to be transferred from the
              application in a single step (up to some system limit, generally
              128K bytes).

Closing notes:

• the big_writes option probably won't help a 4K random write benchmark ;-)
• While Tuxera seem to be reserving the pro NTFS driver for embeded system partners, Paragon offers an alternate free for personal useNTFS driver called NTFS&HFS for Linux 9.0 Express and a professional version. I don't however vouch for this product and when I tried a previous version (v8.5), I could not get it to work with my Linux Kernel version at the time.

Solution 2:

big_writes was deprecated in 2016, the corresponding behavior is always enabled when using libfuse version 3.0.0 or later. On a modern Linux system, poor NTFS performance usually means that:

• the disk is fragmented
• NTFS disk compression is enabled
• inadequate mount options such as sync are used

Solution 3:

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.