Speed testing CF cards with ALIX
--------------------------------
Summary - it doesn't make much difference what you use.
I tried 3 different recently purchased 2GB CF cards for
the ALIX. I did 5 experiments, one trial each. I would
need to do more trials to find average differences that
I could reliably differentiate - nothing was spectacularly
better or worse. I set up a 200MB partition (of which I
am using 3%).
test 1 - initial write of the card, with a Digital Concepts USB
CF programmer. Timed by "dd" output.
test 2 - first boot. This takes a little extra time, as it
zeros blocks in the JFFS partition. I timed the boot manually
from first power to last message.
test 3 - second boot. Time from "reboot" command to last
message, with initial contents.
test 4 - third boot. Same as test 3, except I scp'ed a bunch
of overlay files and additional stuff into the jffs area.
test 5 - UDMA boot. I set the ALIX board to UDMA mode, to
see if that speeds up the card reading (hint - it doesn't)
The cards:
Kingston generic 2GB. This is their basic card. Kingston
claims other versions are faster.
SanDisl Ultra II "15MB/sec"
Results (all times in seconds):
Card Write Boot Boot Boot Boot
test1 test2 test3 test4 test5
Kingston 72? -- 41 46 38
SanDisk 100 160 38 45 39
Transcend 101 151 43 41 42
Conclusion: while there appear to be small differences, they
would probably average out with repeated tests. The speeds
are probably limited by something besides the CF card, such
as DHCP server times, other activities on the computer with
the CF card write on it, etc. I would like to try this out
with a really old camera card (256MB or larger), but I
suspect it doesn't matter a whole lot what gets used;
reliability is probably more important than speed.
Keith
--
Keith Lofstrom [email protected] Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs
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