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dnf -y install hdparm

tar xvf iozone3_489.tar
cd iozone3_489/src/current
make -j5 linux-arm
./iozone -e -I -a -s 100M \
    -r 4k -r 16k -r 512k -r 1024k -r 16384k \
    -i 0 -i 1 -i 2


  • size/serial:
    • udevadm info -a -n /dev/mmcblk0|egrep '{size}|serial|date|name'
    • To find out size, and serial for identification
  • read seq:
    • dd if=/dev/mmcblk0 of=/dev/zero bs=1M count=512
    • To measure sequential read speed
    • Similiar to hdparm -t /dev/mmcblk0
  • rreads/rwrites:
    • iozone -e -I -a -s 100M -r 4k -r 16k -r 512k -r 16384k -i 0 -i 1 -i 2
    • random read/writes, 4kbyte chunks and 512byte chunks
Thinkpad Raspi4
size/serial read seq rreads rwrites read seq rreads rwrites
4/16/512kb4/16/512kb 4/16/512kb4/16/512kb
16G/0x47181309 fed32 Toshiba23MB/sec 5/10/22 0.4/0.1/1.422MB/sec 6/??/22 0.4/??/10
16G/0x000001ed raspb LAZOS45MB/sec 5/16/73 1/3/23 41MB/sec 5/15/38 0.7/3/20
32G/0x00000015 mp3 LAZOS75MB/sec
32G/0x28ca8ad8 nx32 Toshiba82MB/sec 11/23/73 4/11/17
32G/0x7cc4f718 fed32 ELECOM87MB/sec 8/16/72 3/11/17 43MB/sec 8/18/40 4/11/17
32G/070003F3E21C4C65 ELECOM 117MB/sec7/23/104 0.2/0.9/2.6117MB/sec

Cards details

  • 16G/0x47181309, Fedora32 for Raspi4, Toshiba
  • 16G/0x000001ed LAZOS, Raspbian
  • 32G/0x00000015 LAZOS, mp3s
  • 32G/0x28ca8ad8 Toshiba, 02/2018, Nintendo switch L4t/Fedora32
  • 32G/0x7cc4f718 ELECOM MF-BMSD-032, 01/2020, 2000円
  • 32G/070003F3E21C4C65 ELECOM (USBstick), 2000, 2170円


  • USB3 flash is connected with >100MB/sec, and sdcards limited to ~40MB/sec on the Raspi4.
  • USB3 flash sticks can be as slow as sdcards for random access.
  • Profiling typical OS operations, I see many 4kb and 8kb accesses, cards are quite bad at that, they are optimized for sequential access.
  • Cards can be profiled with one reader, and have a comparable profile on other readers. Capping bandwidth wise applies of course, the reader itself can be the bottleneck.
software/benchmark/sdcards.txt · Last modified: 2021/03/23 12:22 (external edit)