MobileRead Forums - View Single Post

DNSB · 08-23-2023, 11:55 AM

I've mentioned this in PMs to a couple of people and had it suggested that I should add this to the start of this thread so here it is:

With the number of small block read/writes Linux does, it's not that greatest match for a SD card. The newer one do have an improved write life but some of the earlier ones had a write life lower than 10,000 cycles. The new units with improved electronics, built-in wear levels and a lot of techniques intended to improve their lifespan can hit at least 100,000 write cycles. Add in a larger card so more blocks to use which extends the lifespan.

One oddity is when your issue is that your ereader still works but you can't send new books to it. This happens since most µSD cards when their write lifespan is exceeded will fail back to being read-only. You can actually create an image from that failed card, write it to a new card and you're back in business. This would involve Windows users not hitting format when Windows complains about the ext4 partitions on the µSD card.

I'm also adding my workflow for creating an image (doing this from memory since I haven't actually written it as a step by step list before and I am trying to add in the steps to allow imaging a Kobo that is having issues:

If your Kobo ereader is not bootable, skip to step 4
Connect over USB and save the current contents of your USB exposed storage.
Do a factory reset (preferably the first level that does not change the firmware version.
Remove the µSD card from your ereader.
Mount the µSD card on your computer. If on Windows, do not format the card. Windows doesn't like ext4 partitions. If you didn't do a factory reset, skip to step 7
Copy the contents of the FAT32 partition to your computer.
Do a full format on the FAT32 partition. This will remove any information such as books that are not removed during the quick format. Skip to step 9 if a factory reset wasn't done.
Copy the contents of the FAT32 partition from step 5 back to FAT32 partition.
Create an image of the card. If the image will not create, stop and request an image. If you are planning on sharing the image, use a hex editor to remove the serial number located at 0x200 in the image. I use HxD.
Create an archive of the image. With the FAT32 partition cleaned up, the image will be a lot smaller.
If your Kobo was not booting, image a new µSD card from your image.
Re-install the µSD card into your Kobo, connect it to your computer. If it doesn't power on automatically, power it on.
When the connect/cancel popup pops up, tap connect
Copy the saved contents of the FAT32 partition from step 1(factory reset) or step 6 (no factory reset) back to your Kobo.
Share the image with others.

08-23-2023, 11:55 AM	#2
DNSB Bibliophagist Posts: 46,355 Karma: 169098492 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	I've mentioned this in PMs to a couple of people and had it suggested that I should add this to the start of this thread so here it is: With the number of small block read/writes Linux does, it's not that greatest match for a SD card. The newer one do have an improved write life but some of the earlier ones had a write life lower than 10,000 cycles. The new units with improved electronics, built-in wear levels and a lot of techniques intended to improve their lifespan can hit at least 100,000 write cycles. Add in a larger card so more blocks to use which extends the lifespan. One oddity is when your issue is that your ereader still works but you can't send new books to it. This happens since most µSD cards when their write lifespan is exceeded will fail back to being read-only. You can actually create an image from that failed card, write it to a new card and you're back in business. This would involve Windows users not hitting format when Windows complains about the ext4 partitions on the µSD card. I'm also adding my workflow for creating an image (doing this from memory since I haven't actually written it as a step by step list before and I am trying to add in the steps to allow imaging a Kobo that is having issues: If your Kobo ereader is not bootable, skip to step 4 Connect over USB and save the current contents of your USB exposed storage. Do a factory reset (preferably the first level that does not change the firmware version. Remove the µSD card from your ereader. Mount the µSD card on your computer. If on Windows, do not format the card. Windows doesn't like ext4 partitions. If you didn't do a factory reset, skip to step 7 Copy the contents of the FAT32 partition to your computer. Do a full format on the FAT32 partition. This will remove any information such as books that are not removed during the quick format. Skip to step 9 if a factory reset wasn't done. Copy the contents of the FAT32 partition from step 5 back to FAT32 partition. Create an image of the card. If the image will not create, stop and request an image. If you are planning on sharing the image, use a hex editor to remove the serial number located at 0x200 in the image. I use HxD. Create an archive of the image. With the FAT32 partition cleaned up, the image will be a lot smaller. If your Kobo was not booting, image a new µSD card from your image. Re-install the µSD card into your Kobo, connect it to your computer. If it doesn't power on automatically, power it on. When the connect/cancel popup pops up, tap connect Copy the saved contents of the FAT32 partition from step 1(factory reset) or step 6 (no factory reset) back to your Kobo. Share the image with others. Last edited by DNSB; 05-28-2025 at 07:17 PM.