On 27/03/13 00:13, Greg Freemyer wrote:
Basil Chupin <blchupin(a)iinet.net.au> wrote:
> I bought a Seagate 2TB USB3 external HDD today and formatted 75% of
> with ext4 file system and 25% with ntfs -
using latest version of
> My two internal 1TB Seagates are SATA 3 and formatted with ext4
> for one partition (ntfs) which has XP
installed, but which is rarely
> used (it's mainly there to bring me back to earth and to remind me
> bloody aweful Windows is).
> I use mc (Midnight Commander) 99.99% of the time to manage my files.
> After I formatted the external HDD (as described above) I went to
> files from my main system to the new external
HDD - which is to be
> for backups.
> What I found - and which is what I am now asking about - is that
> using mc, that when copying files to the
*ext4* formatted partition
> files where being copied across at ~80MB/s. The files copied over
> mixture of ntfs and ext4 files (which I had copied from a collapsing
> 32-bit system to my current *Linux* system last year when I replaced
> old computer).
> However, when I went to copy files to the *ntfs* formatted part of
> new external HDD, the best transfer rate I
got was ~28MB/s - which
> very much like what I used to get when using USB2!
> So, why the *big* difference in transfer rates between copying files
> a partition formatted in *ext4* and one formatted in *ntfs*?!
> What system am a I using? Look at my signature line; but I
> that some brain-dead mail clients drop the
signature line so for
with brain-dead mailers the sig. line is:
Using openSUSE 12.3 x86_64 with KDE 4.10.1 & kernel 3.8.4-1
Any suggestions, please, as to why there is such a difference in the
transfer rates between the 2 file systems, and how can this be
Ntfs-3g is a fuse based filesystem.
Thanks, Greg, but it's over it's over my head :-( . What's a fuse based
That means the filesystem code actually is a
userspace app, not a
kernel module like most linux filesystems.
And again, way over my head: what is a "userspace app"?
Without getting complex, a linux based computer runs kernel code and userspace code. If
you have data in the kernel and you need it in userspace, then typically you have to copy
it from the kernel to userspace. That takes time. And if you need it back in the kernel,
you have to copy it again (ie. More time).
I don't know if fuse has any special accelerator techniques, but in general when
people want top performance they write the code to be part of the kernel. The trouble is
the kernel is very dynamic and code has to maintained much more actively.
The ntfs-3g devs have chosen ease of development/support over performance.
I think that
makes it inherently slower. Anyway, before you assume
something is wrong with your
system you should research what
performance to expect from ntfs-3g.
OK, I'll go checking what performance one can expect from ntfs-3g but
it worked in USB 2 conditions then why shouldn't it work in USB 3
Assume your 28MB/sec performance is the fastest ntfs-3g can run on your computer. Usb-2
maxes out a little below that, so usb-2 was the bottleneck. Usb-3 is a lot faster, so now
ntfs-3g is your bottleneck.
If you find I'm wrong about ntfs-3g being the problem, please let us know. I too hit
this bottleneck a lot.
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