[clug] OT - USB flash timings

[Duncan Roe]

Yes, flash has to erase a sector and rewrite in order to make any change to it.
Therefore many short writes will be very slow.

Cheers ... Duncan.

On Sat, Jun 16, 2007 at 03:56:08PM +1000, steve jenkin wrote:
> I got a question from a cousin about his new USB flash taking an age to
> copy something...
> Thought the group might be interested...
>
> Seems standard devices are very sensitive to block size on *write* - but
> not on read...
>
> For some good reference material: Wikipedia and Kingston:-
>
> <http://www.kingston.com/products/pdf_files/FlashMemGuide.pdf>
> <http://en.wikipedia.org/wiki/Flash_Memory>
>
>
> Device used for these tests: 4Gb Kingston 'Data Traveller'.
> 512Mb file used for most timings (1Mb for 1b test).  No FileSystem Cache
> issues.
>
> > USB Flash - WRITE performance
> >    1b    88,827 bytes/sec
> >    8k 1,035,601 bytes/sec
> >  128k 3,819,827 bytes/sec
> >  512k 4,155,635 bytes/sec
> >
> > USB Flash - READ performance
> >    8k 9,467,708 bytes/sec
> >   16k 9,448,265 bytes/sec
> >   32k 9,386,199 bytes/sec
> >   64k 9,475,763 bytes/sec
> >  128k 9,466,469 bytes/sec
> >  256k 9,453,077 bytes/sec
> >  512k 9,415,421 bytes/sec
> > 1024k 9,482,868 bytes/sec
> Hope this is interesting/helpful.
>
> regards
> stevej
>
> --
> Steve Jenkin, Info Tech, Systems and Design Specialist.
> 0412 786 915 (+61 412 786 915)
> PO Box 48, Kippax ACT 2615, AUSTRALIA
>
> sjenkin at canb.auug.org.au http://www.canb.auug.org.au/~sjenkin
>
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