Re: Extremely poor umass transfer rates

From: J.A. Magallon
Date: Fri Apr 29 2005 - 06:54:19 EST

On 04.28, Tomasz Torcz wrote:
> On Thu, Apr 28, 2005 at 07:55:40PM +0200, Mark Rosenstand wrote:
> > The line that 'hald' puts in fstab looks like this:
> >
> > /dev/sdb /media/usbdisk vfat \
> > user,exec,noauto,utf8,noatime,sync,managed 0 0
> Are you sure it's correct? I can't even mount with those options:
> #v+
> # mount /dev/sdb1 /mnt/other -t vfat -o user,exec,noauto,utf8,noatime,sync,managed
> mount: wrong fs type, bad option, bad superblock on /dev/sdb1
> missing codepage or other error
> In some cases useful info is found in syslog - try
> dmesg | tail or so
> # dmesg | tail -2
> usb-storage: device scan complete
> FAT: Unrecognized mount option "managed" or missing value
> #v-
> Omitting "managed" seems to work. But it's slooow:
> # dd if=/dev/zero bs=1M count=100 | pv > /mnt/other/100MB
> 1,17MB 0:00:28 [41,7kB/s] [ <=> ]
> It stays at about 40 kB/s during all transfer.
> Reading is as fast as it should be = about 18 MB/s (after umount, mount
> again, to clear cache).

Je, je, you're dreaming. The limit on pendrives, flash mp3 players and so
on is the flash memory read/write speed. You are lucky if you get 1Mb/s.
So for a flash based device, dont ever worry about if it is USB 1.1 or 2.0.
Things are different if you have a disk based device (iPod, iPod mini).
A disk is a disk.

The difference in total time should be minimal between sync and async mounts,
if you take into account filesystem sync/umount time.

Anyways, your 40 Kb/sec seem too sloow. But dont expect your 19Mb/s, only
about 1Mb/s (reading, writing thigs drop to 600Kb/s).


J.A. Magallon <jamagallon()able!es> \ Software is like sex:
werewolf!able!es \ It's better when it's free
Mandriva Linux release 2006.0 (Cooker) for i586
Linux 2.6.11-jam14 (gcc 4.0.0 (4.0.0-1mdk for Mandriva Linux

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