SanDisk micro SDHC 8GB card under testing

ian douglas ian.douglas at iandouglas.com
Fri Jul 11 00:56:41 CEST 2008


ian douglas wrote:
> I'll try Mike's iospeed utility next, but here's a dual-run of the
> bonnie++ utility:

I should mention too that before running bonnie++ or Mike's utility,
that I deleted the FAT32 partition on the 8GB card, created a single
primary type-83 Linux partition and formatted it ext3. Since I rarely
run Windows at home any more, I didn't see any need to continue to use
vfat-formatted memory cards.


Mike Montour wrote:
> http://members.shaw.ca/mmontour/neo/iospeed is a simple
> performance-test program that I wrote (source is "iospeed.c" in the
> same directory)

Mike, your binary is 420kb ... I'm guessing that you compiled your code
with the cross-compiler toolchain?

After installing gcc/g++ and stdlib stuff via opkg on the Freerunner, I
was able to compile the utility directly on the Freerunner and it came
out to only 15kb.

Either way, here's my results with the 8GB SDHC card:

root at om-gta02:/media/card# wget \
http://members.shaw.ca/mmontour/neo/iospeed

root at om-gta02:/media/card# chmod +x iospeed

root at om-gta02:/media/card# wget \
http://members.shaw.ca/mmontour/neo/iospeed.c

root at om-gta02:/media/card# gcc iospeed.c -o iospeed2

root at om-gta02:/media/card# ls -l
-rwxr-xr-x    1 root     root       418384 Jul 10 21:08 iospeed
-rw-r--r--    1 root     root         2444 Jul 10 21:08 iospeed.c
-rwxr-xr-x    1 root     root        14758 Jul 10 21:19 iospeed2

root at om-gta02:/media/card# ./iospeed2
usage: ./iospeed2 <filename> <size-in-MiB>

I moved the iospeed files to /opt/ so I could compare against the 512MB
card that shipped with the Freerunner, and ran Mike's utility three
times on the 8GB SDHC card:

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)      Write (MiB/s)   Read (MiB/s)
100     0.776   8.890

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)      Write (MiB/s)   Read (MiB/s)
100     1.566   9.417

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	1.557	9.396

and once on the unit's own Flash ROM as a comparison:
root at om-gta02:/media/card# cd /opt
root at om-gta02:/var/volatile/opt# /opt/iospeed2 testfile 50
Size (MiB)	Write (MiB/s)	Read (MiB/s)
50	1.577	9.530

Then tested /tmp which I guess is a RAM drive considering the speed boost:

root at om-gta02:/media/card# cd /tmp
root at om-gta02:/var/volatile/tmp# /opt/iospeed2 testfile 50
Size (MiB)	Write (MiB/s)	Read (MiB/s)
50	28.617	42.786


The 512MB card that came with my Freerunner has some other files on it,
and is formatted as vfat/FAT32. I ran the iospeed utility there three
times as well:

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	2.020	2.739

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	2.187	2.743

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	2.207	2.736


So according to Mike's utility, writing the the 8GB card is slightly
faster, but reading is several times slower reading the 512MB card.

I was curious if this was a vfat vs ext3 performance hit, so I deleted
the partition on the 512MB card, built a primary type 83 partition,
formatted it ext3 and re-ran the iospeed tests:

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	1.789	2.495

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	1.722	2.505

root at om-gta02:/media/card# /opt/iospeed2 testfile 100
Size (MiB)	Write (MiB/s)	Read (MiB/s)
100	1.786	2.478

So interestingly enough, writes were slower on ext3 than vfat on the
512MB card.




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