CF Speed (was Re: Experience Using Flash + USB For SSH Keys?)

Alex Satrapa grail at
Tue Dec 3 13:46:58 EST 2002

On Tue, 2002-12-03 at 11:01, Bob Edwards wrote:
> ... re-writing of the atime field for each file read is not 
> only going to wear out your CF card, but it is also slow (writing to flash is 
> generally slow).

For those who are interested, here is a speed comparison of some CF
cards (none of which I have by the way ;)  This comparison is especially
meaningful to me since I have a Nikon Coolpix 995 camera. +

For my immediate needs - as a repository for SSH keys - the 16MB card
that came with my camera is more than adequate.  It's slow^ - that's
probably just the USB interface, rather than the card itself - but speed
doesn't matter for loading SSH keys.

For my longer term needs - as storage for pictures I'm taking with my
"prosumer*" digital camera, or as boot media for my silent internet
connection box - I'd probably invest in the Ridata 512MB card, since
speed is everything for the camera, and very useful for getting a Linux
box booted as quickly as possible.

FYI, Fletcher's Fotographics in Civic stock Ridata cards.

+  "JPEG" on a 995 is rather meaningless without specifying the
compression level used (Basic/Normal/Fine), since higher compression
will take more time due to CPU load.  TIFF is the Nikon's native
uncompressed mode, so it gives a better indication of controller/card

^  As an illustration of slow/fast for CF. In the Nikon Coolpix 995
storing a 1.2MB JPEG to CF takes 5 seconds for the Nikon rebadged
Sandisk 16MB CF, 1.5 seconds for Apacer 64MB CF and 5 seconds for PQI
128MB CF. Using the same cards under Linux to transfer a 1.7MB PDF file
(using "time (cp file /tanya/CF-Card ; sync; rm /tanya/CF-Card/file;
sync)") took 6.3s, 7.2s and 5.9s respectively - so there's more to the
scenario than just the CF itself - the only realistic "benchmark" is to
test candidate CF in the exact scenario that you're going to use it.

* In the sense of "consumer looking for high-end features normally found
in professional level equipment" rather than "consumer who also
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