Card speed issues

[sunbit]

I have speed issues copying to/from a pISO drive:

• SD card is a Samsung EVO Plus 128 Gb, class 10.
• Copy tests done with a single 4.57 Gb file.
• v1.2 firmware

Testing with the raw sdcard, 1 partition of 128GB ExFat:

• Write speed: 77 Mb/s
• Read speed: 97 Mb/s

Testing with a single drive created in pISO, 100% of capacity

• Write speed: 5.5 Mb/s
• Read speed: 14 Mb/s

I don't now if this can be caused by the raspberry pi or the pISO, but as you can see I have a 15x difference between copying files to/from the raw sdcard, vs copying files from a drive defined using pISO with the same card.

Any idea?

Thank you

[appcoders]

Yes would be interesting if its a Raspi hardware issue...

[xela92]

I'm facing this issue too, I have Samsung EVO Plus 128GB too, and I'm doing less then 5 MB/s writing.

[Willena]

I've also faced this issue. I looked through the internet and here is what I found

http://www.pidramble.com/wiki/benchmarks/microsd-cards

There is nothing about the Pi Zero itself but I think it's similar to other Pis.
Most interestingly this is the of the last sentence of the author :

(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)

I found this thread https://stackoverflow.com/a/23164364/4346098 it might also be interesting

[extremeshok]

Create the volume as ext3 and test, the ntfs/fat32 is extremely slow.

im getting a 3x boost with ext3.

[Willena]

I've been trying things today and found out that things can somehow probably be improved.

Before anything, here are the measurements made using the pISO:

• Read : ~17MB/s
• Write: ~5MB/s

I tested the read and write speed of my micro sdcard from a fresh install of raspbian, using the script in this thread. The result I got were encouraging !

• Read : ~18MB/s
• Write: ~17MB/s

As suggested by the thread, I added the dtparam=sd_overclock=100 in my /boot/config.txt. The previous results has almost doubled:

• Read: ~38MB/s
• Write: ~32MB/s

This shows us that USB read write are being slowed by either LVM or the usb_gadget module (g_mass_storage). pISO is runnning on usb_gadget module of the kernel. pISO seams to be also using LVM for the drive management (please correct me if i'm wrong).

Using only a bin file NTFS formated and usb mounted (modprobe g_mass_storage file=/data/file.bin ro=0 stall=0) I got:

• Read: 31Mb/s
• Write: 10-17Mb/s
  These read write speed even if they are slower than what the raspberry pi can handle (see second sdcard test, with dtparam=sd_overclock=100) are more acceptable. For the moment theses are just measurement and tests. It seams that the only thing left to test is LVM...

To be continued 😄