Basil Chupin <blchupin@iinet.net.au> wrote:
On 27/03/13 00:13, Greg Freemyer wrote:
Basil Chupin <blchupin@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 Gparted.
My two internal 1TB Seagates are SATA 3 and formatted with ext4 except 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 how 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 copy files from my main system to the new external HDD - which is to be used
for backups.
What I found - and which is what I am now asking about - is that when, using mc, that when copying files to the *ext4* formatted partition
files where being copied across at ~80MB/s. The files copied over
were
a 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 the 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 looks very much like what I used to get when using USB2!
So, why the *big* difference in transfer rates between copying files to
a partition formatted in *ext4* and one formatted in *ntfs*?!
What system am a I using? Look at my signature line; but I understand that some brain-dead mail clients drop the signature line so for
it the the these
people 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 overcome?
BC Basil,
Ntfs-3g is a fuse based filesystem.
Thanks, Greg, but it's over it's over my head :-( . What's a fuse based
filesystem?
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.
Greg
OK, I'll go checking what performance one can expect from ntfs-3g but if it worked in USB 2 conditions then why shouldn't it work in USB 3 conditions?
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.
BC
If you find I'm wrong about ntfs-3g being the problem, please let us know. I too hit this bottleneck a lot. Greg -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org