microSD Card Benchmarks

In my experience, one of the highest-impact upgrades you can perform is to buy the fastest possible microSD card—especially for applications where you need to do a lot of random reads and writes.

There is an order-of-magnitude difference between most cheap cards and the slightly-more-expensive ones (even if both are rated as being in the same class)—especially in small-block random I/O performance. As an example, if you use a normal, cheap microSD card for your database server, normal database operations can literally be 100x slower than if you used a standard microSD card.

Because of this, I went and purchased over a dozen different cards and have been putting them through their paces. Here are the results of those efforts, in a nice tabular format:

Pi models tested

Click on a Pi model to see microSD benchmarks run on that Pi.

Rasbperry Pi 4 model B
Rasbperry Pi 3 model B+
Rasbperry Pi 3 model B
Rasbperry Pi 3 model B - overclocked microSD
Rasbperry Pi 2 model B

Rasbperry Pi 4 model B

Card Make/Model	`hdparm` buffered	`dd` write	4K rand read	4K rand write
Samsung Pro+ 32GB	43.90 MB/s	39.6 MB/s	10.77 MB/s	2.61 MB/s
Samsung Pro Endurance U1 32GB	43.52 MB/s	37.4 MB/s	10.21 MB/s	2.83 MB/s
Samsung Pro 16GB	43.86 MB/s	38.6 MB/s	10.49 MB/s	1.74 MB/s
Samsung Evo Plus 64GB	43.45 MB/s	22.4 MB/s	7.93 MB/s	2.37 MB/s
Samsung Evo+ 32GB	43.92 MB/s	21.3 MB/s	10.80 MB/s	3.85 MB/s
Samsung Evo 16GB	43.40 MB/s	12.1 MB/s	7.09 MB/s	1.24 MB/s
NOOBS (1.4, C6) 8GB	43.15 MB/s	6.6 MB/s	7.14 MB/s	1.05 MB/s
SanDisk Extreme U3 V30 A2 64GB	43.73 MB/s	36.3 MB/s	7.35 MB/s	3.70 MB/s
SanDisk Extreme Pro A1 32GB	43.87 MB/s	38.8 MB/s	9.82 MB/s	4.70 MB/s
SanDisk Extreme Pro 8GB	43.78 MB/s	35.5 MB/s	9.22 MB/s	1.25 MB/s
SanDisk Extreme 16GB	43.95 MB/s	39.5 MB/s	9.46 MB/s	2.46 MB/s
SanDisk Ultra 16GB	42.30 MB/s	8.2 MB/s	6.57 MB/s	1.52 MB/s
Lexar Professional U3 A2 V30 128GB	44.35 MB/s	32.4 MB/s	9.65 MB/s	2.55 MB/s
Sony C10 U3 32GB	40.78 MB/s	35.7 MB/s	1.58 MB/s	0.66 MB/s
Toshiba C10 U1 16GB	41.62 MB/s	12.0 MB/s	6.62 MB/s	0.22 MB/s

Rasbperry Pi 3 model B+

Card Make/Model	`hdparm` buffered	`dd` write	4K rand read	4K rand write
Samsung Pro+ 32GB	21.89 MB/s	19.7 MB/s	8.59 MB/s	2.14 MB/s
Samsung Pro 16GB	21.85 MB/s	21.6 MB/s	8.42 MB/s	1.34 MB/s
Samsung Evo Plus 64GB	21.71 MB/s	19.5 MB/s	7.87 MB/s	2.33 MB/s
Samsung Evo+ 32GB	21.98 MB/s	15.8 MB/s	8.63 MB/s	3.17 MB/s
Samsung Evo 16GB	18.62 MB/s	11.3 MB/s	5.73 MB/s	0.93 MB/s
NOOBS (1.4, C6) 8GB	18.81 MB/s	6.5 MB/s	6.35 MB/s	0.99 MB/s
SanDisk Extreme Pro 8GB	22.06 MB/s	20.2 MB/s	8.16 MB/s	1.21 MB/s
SanDisk Extreme 16GB	22.15 MB/s	20.6 MB/s	8.31 MB/s	2.21 MB/s
SanDisk Ultra 16GB	21.09 MB/s	8.2 MB/s	5.93 MB/s	1.57 MB/s
Sony C10 U3 32GB	19.51 MB/s	18.5 MB/s	2.26 MB/s	0.65 MB/s

Rasbperry Pi 3 model B

Card Make/Model	`hdparm` buffered	`dd` write	4K rand read	4K rand write
Samsung Pro+ 32GB	21.88 MB/s	20.2 MB/s	9.61 MB/s	2.16 MB/s
Samsung Pro 16GB	21.62 MB/s	22.1 MB/s	9.41 MB/s	1.66 MB/s
Samsung Evo+ 32GB	21.77 MB/s	15.8 MB/s	9.66 MB/s	3.43 MB/s
Samsung Evo Select 32GB	19.59 MB/s	5.7 MB/s	4.34 MB/s	0.71 MB/s
Samsung Evo 16GB	20.08 MB/s	10.4 MB/s	6.02 MB/s	1.02 MB/s
SanDisk Extreme Pro 8GB	21.02 MB/s	21.2 MB/s	9.07 MB/s	1.25 MB/s
SanDisk Extreme 16GB	22.08 MB/s	21.8 MB/s	9.44 MB/s	2.42 MB/s
SanDisk Ultra 16GB	20.79 MB/s	7.9 MB/s	5.98 MB/s	1.57 MB/s

Rasbperry Pi 3 model B - overclocked microSD

You can double the microSD card reader's speed by adding an extra dtoverlay configuration inside /boot/config.txt (for instructions, see How to overclock the microSD card reader in the Raspberry Pi 3).

Card Make/Model	`hdparm` buffered	`dd` write	4K rand read	4K rand write
Samsung Pro+ 32GB	39.93 MB/s	31.0 MB/s	12.15 MB/s	1.84 MB/s
Samsung Pro 16GB¹	31.59 MB/s	32.8 MB/s	11.20 MB/s	1.48 MB/s
Samsung Evo+ 32GB	37.68 MB/s	20.0 MB/s	12.20 MB/s	3.75 MB/s
Samsung Evo Select 32GB	24.56 MB/s	13.2 MB/s	4.69 MB/s	0.82 MB/s
Samsung Evo 16GB	32.47 MB/s	11.8 MB/s	6.44 MB/s	1.25 MB/s
SanDisk Extreme Pro 8GB	40.52 MB/s	35.9 MB/s	11.31 MB/s	1.28 MB/s
SanDisk Extreme 16GB	40.88 MB/s	39.1 MB/s	11.77 MB/s	2.36 MB/s
SanDisk Ultra 16GB	37.41 MB/s	8.5 MB/s	6.71 MB/s	1.61 MB/s

¹ The Samsung Pro refused to overclock to 100 MHz; I could only overclock at 80 MHz reliably.

Rasbperry Pi 2 model B

Card Make/Model	`hdparm` buffered	`dd` write	4K rand read	4K rand write
OWC Envoy SSD (USB) 64GB	34.13 MB/s	34.4 MB/s	7.06 MB/s	8.20 MB/s
SanDisk Ultra Fit (USB) 32GB	31.72 MB/s	14.5 MB/s	4.99 MB/s	1.07 MB/s
Samsung Pro+ 32GB	21.75 MB/s	18.7 MB/s	8.31 MB/s	1.75 MB/s
Samsung Pro 16GB	18.39 MB/s	18.2 MB/s	7.66 MB/s	1.01 MB/s
Samsung Evo+ 32GB	18.45 MB/s	14.0 MB/s	8.02 MB/s	3.00 MB/s
Samsung Evo 16GB	17.39 MB/s	10.4 MB/s	5.36 MB/s	1.05 MB/s
SanDisk Extreme Pro 8GB	18.43 MB/s	17.6 MB/s	7.52 MB/s	1.18 MB/s
SanDisk Extreme 16GB	18.51 MB/s	18.3 MB/s	8.10 MB/s	2.30 MB/s
SanDisk Ultra 16GB	17.73 MB/s	7.3 MB/s	5.34 MB/s	1.52 MB/s
NOOBS (1.4, C6) 8GB	17.62 MB/s	6.5 MB/s	5.63 MB/s	1.01 MB/s
Transcend Premium 300x 32GB	18.14 MB/s	10.3 MB/s	5.21 MB/s	0.84 MB/s
PNY Turbo (C10 90MB/s) 16GB	17.46 MB/s	TODO	6.25 MB/s	0.62 MB/s
Toshiba (C10 40MB/s) 16GB	17.66 MB/s	11.2 MB/s	5.21 MB/s	0.21 MB/s
Sony (C10 70MB/s) 16GB	15.38 MB/s	8.9 MB/s	2.47 MB/s	0.24 MB/s
Kingston (C10) 16GB	17.78 MB/s	9.0 MB/s	5.75 MB/s	0.21 MB/s
Kingston (C10) 8GB	12.80 MB/s	7.2 MB/s	5.56 MB/s	0.17 MB/s
Nasya (C10) 16GB	16.05 MB/s	8.4 MB/s	2.28 MB/s	0.38 MB/s
No-name (C4) 4GB	13.37 MB/s	Sad	Painful	Excruciating

Benchmarks

All the benchmarks can be run quickly and easily by running a shell script in the Raspberry Pi Dramble repository:

curl https://raw.githubusercontent.com/geerlingguy/raspberry-pi-dramble/master/setup/benchmarks/microsd-benchmarks.sh | sudo bash

`hdparm` buffered

sudo hdparm -t /dev/mmcblk0

Rationale: hdparm gives basic raw throughput stats for buffered reads (by the disk/device itself). You could also test with -T instead of -t to test the OS filesystem cache performance (which allows the OS to dramatically speed up certain read operations), but for our purposes we just want to test the device itself.

Setup:

Install hdparm: sudo apt-get install -y hdparm

`dd` write

sudo dd if=/dev/zero of=/home/pi/test bs=8k count=50k conv=fsync; sudo rm -f /home/pi/test

Rationale: dd simply copies data from one place (if) to another (of). If your filesystem caches are big enough, this is a pretty poor disk speed comparison test. Because of that, make sure that count is set to a parameter large enough to cause the OS to actually write data to the drive (e.g. 50k 8k blocks ~= 400 MB, which shouldn’t be able to be cached on a microSD card in a Pi!.

`iozone` 4K Random read/write

iozone -e -I -a -s 100M -r 4k -i 0 -i 1 -i 2 [-f /path/to/file]

Rationale: iozone is a very robust filesystem benchmark tool, which does a lot of useful tests that make sure you’re getting a broad overview of read and write performance for a variety of block sizes and situations. I like the lower block size random I/O tests especially, because many operations (like logging data, writing a row to an ACID-compliant database, or bulk loading of data) require as fast of small-block-size random I/O as possible.

Most cheap microSD cards, even if rated as being 100MB/sec+ class 10 cards, can’t sustain anywhere near that rate when writing random data—especially on the Raspberry Pi’s measly data bus. (Note that most of the above benchmarks, when run on a USB 3.0 card reader on my MacBook Air, show 5, 10, or 15 times greater performance in that environment).