Arch Linux

brisbin33

Member

From: boston, ma

Registered: 2008-07-24

Posts: 1,799

Website

USB seems slow... am i crazy?

I'm not really a linux newbie but this seems a newbie question so...

i have a 1-1/2 year old external USB HD formatted to ext3 that i use for music / movies / etc. 

when using it in arch, copying files just felt slow to me, so i did some investigating...

timing a file transfer USB>>PC yielded:

2.23 minutes for a 2.6 GB folder. that's 1.09 GB/m (too fast to be plugged into a low speed port)

my research finds that USB 2.0 has a limit of 480 Mbits/s but a "typical sustained speed of 240 Mbits/s"

that works out to 3.515 GB/m and 1.757 GB/m respectively

should i be worried that i'm only getting ~60% of "typical" or "realistic" USB 2.0 speeds? or can that simply be chalked up to 1-1/2 years old?

(i'm using the nifty udev rules from the wiki to automount USB devices)

not looking for a "solution" so much as comments and discussion.

thanks in advance.

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phrakture

Arch Overlord

From: behind you

Registered: 2003-10-29

Posts: 7,879

Website

Re: USB seems slow... am i crazy?

What mount options are you using to mount the external drive? I've noticed huge performance degradation with the "sync" option (obviously)

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brisbin33

Member

From: boston, ma

Registered: 2008-07-24

Posts: 1,799

Website

Re: USB seems slow... am i crazy?

you're right the relevant mount command from my udev rules would be:

RUN+="/bin/mount -t auto -o rw,noauto,async,dirsync,noexec,nodev,noatime /dev/%k /media/usbhd-%k", OPTIONS="last_rule"

async and dirsync could be the slowdown...

would you recommend better options?

EDIT: seems enabling full journaling and directory indexing as per this could speed up my transfers.  does anyone know if i can do this on my HDD without risk of losing data (i don't have a second drive large enough to back it up if i wanted to try it).

once i learn more about what's actually going on with my ext3 fs, i could more intelligently select the mount options and have a specific entry for ext3 file systems (like the vfat one in the udev wiki)

thanks

Last edited by brisbin33 (2008-09-08 18:30:09)

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