[BUG]: The image writing page stays at 100% for more than 10 minutes before verification starts.

[salmanfarisvp]

What happened?

The image writing page stays at 100% for more than 10 minutes before verification starts. I observe similar behaviour with other custom OS as well, but faster in the official OS.

To reproduce

• Download Pi Imager v2.0.0
• Download a Raspberry Pi-compatible OS
• Flash the image to an SD card using the custom image option.
• After it reaches 100%, it appears to be stuck for more than 10 minutes.

Version

2.0.0 (Default)

What host operating system were you using?

macOS

Host OS Version

26.1 (25B78)

Selected OS

Custom Image

Which Raspberry Pi Device are you using?

Raspberry Pi 4B, 400, and Compute Modules 4, 4S

What kind of storage device are you using?

microSD Card in a USB reader

OS Customisation

• Yes, I was using OS Customisation when the bug occurred.

Relevant log output

[lurch]

It sounds like perhaps the OS has buffered up a bunch of pending writes in memory, and the 10 minute delay is waiting for all those pending writes to actually be flushed out to the SD card? Imager 2.0 definitely shouldn't be doing this though, it's supposed to periodically flush pending writes to the SD card during the writing process, precisely to prevent this "huge write all at the end" behaviour.
How big is the custom image you're flashing? How big is your SD card? What "speed rating" does your SD card have? How much RAM do you have in your Mac?

Imager 2.0.2 (not released yet) will have enhanced performance logging, which will help to more accurately diagnose issues like this.

[salmanfarisvp]

Hi @lurch, Thanks for the comment.

How big is the custom image you're flashing?

1.11GB

How big is your SD card?

64GB, A2 Card

What "speed rating" does your SD card have?

SanDisk Extreme Pro 64GB A2, read speeds up to 200MB/s and writes up to 140MB/s.

How much RAM do you have in your Mac?

16GB.

I noticed similar behaviour when choosing a custom image directly from the Raspberry Pi Imager; however, using the official Raspberry Pi image with the same setup results in smooth and quick performance.

[lurch]

How big is the custom image you're flashing?

1.11GB

Is that the compressed or uncompressed size? If it's a compressed image, what file-format is it? If you manually decompress the image, how big is it then, and is Imager any "smoother" when writing the uncompressed image?

[salmanfarisvp]

Is that the compressed or uncompressed size? If it's a compressed image, what file-format is it?

Compressed, ZIP format.

As I mentioned, I experienced the same issue when trying to use any third-party operating system through the imager, but it works very well with Etcher.

I also tested the same image with the previous version of Raspberry Pi Imager, and it worked without any problems. It seems that the issue lies with the newest version.

[ZhuDaHai]

Maybe this will help:
32GB Pi disk image backup compressed to 883MB
88% complete in ~10 mins
Next 10% in another 10 mins
Over 1 Hour for the last 2% (screenshot below shows Drive Activity during that last 2%)
Samsung 64GB EVO Select Micro SDXC IU3