Nick Rout wrote: > I have an imation 4G flash drive that is sitting in a USB2 port. I am > transferring a 3.7G file from the computers sata hard drive to the usb > drive. > > It seems to be taking about 20 minutes This seems far too long. USB > data rate 60MB/s. > > 3719MB/60MB/s = 62 seconds, give or take. > > Now I know I won't get a sustained rate anywhere near that, but the > predicted time is 20 odd times over the theoretical minimum time. > > So where should I look for problems. Suspicions centre around: > > 1. USB flash drive cannot handle the data rate, tough one Nick; or > > 2. USB operating at USB1.1 rate only. How would I diagnose that? > > Its an intel based compaq motherboard, excerpts from lspci: > > 00:1d.0 USB Controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB > UHCI Controller #1 (rev 02) > 00:1d.1 USB Controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB > UHCI Controller #2 (rev 02) > 00:1d.2 USB Controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB > UHCI Controller #3 (rev 02) > 00:1d.7 USB Controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB2 > EHCI Controller (rev 02) > > dmesg displays a lot of lines with the term USB in them, dunno whats relevant. >
Another point of reference is the relative speed rating of CF and SD cards. They are often rated as 6x or 60x or 133x. This is relative to the standard CD ROM 1x speed of 150 k bytes/sec. (http://en.wikipedia.org/wiki/SD_card#Speeds) So an SD card rated at 6x can transfer data at 900 k bytes/sec, while a 60x card can get close to 10 M bytes/sec. Top end cards (133x or 150x) can get up to perhaps 20 or 30 M bytes/sec. It is not clear from Wikipedia or manufacturer's very limited datasheets whether this is read speed or write speed; one assumes the read speed because this is usually higher than the write speed. Stephen Irons ======================================================================= This email, including any attachments, is only for the intended addressee. It is subject to copyright, is confidential and may be the subject of legal or other privilege, none of which is waived or lost by reason of this transmission. If the receiver is not the intended addressee, please accept our apologies, notify us by return, delete all copies and perform no other act on the email. Unfortunately, we cannot warrant that the email has not been altered or corrupted during transmission. =======================================================================
