Looks like there's a FS within the FS

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
1

Hi Community,

I’ve used the latest Jetson Nano image from Nvidia and found out that:

  • MicroSD card is mounted as /sda and has a more or less 56Gb free storage left
  • The image created a mmblk0 device where the root account lives, which is only 14Gb.

This capacity is not enough for our application: why can’t I just use the /sda/home/myuser to install the application? Why am I restricted into this mmblk0 device (which I don’t need at all)?

I’m new to Ubuntu, so please explain slowly! 😁

Thanks in advance for any help!

2

Wrong forum, please try:
https://forums.developer.nvidia.com/c/agx-autonomous-machines/jetson-embedded-systems/jetson-nano/76

3

I will move this topic to the Jetson forums.

4

Thanks a lot and sorry for the mistake!

6

Hi, you should first know how file system in Linux works:
partitions and mounting points are two different things.

If you would like to use the SD card for your home folder, you should modify /etc/fatsb,
and mount sda1 as /home, whereas mmcblk0p1 is mounted as /.

Or if you don’t mind re-flashing, you can also flash the image into the SD card,
and have it mounted as the RootFS.

7

Thanks for the advice! I’ve actually begun reading on Linux filesystem as I understood I was missing something here…

By the way, on this particular case, many files have been copied to the current home folder (/nvidia/Documents or /nvidia/Images): would the modification you suggest move those files to the new location or would they be lost in the migration?

8

Hi, you can follow convert-home-directory-partition-linux, and start from Step 4 as you already have your SD card formatted.

So basically what you need to do is:

  1. Create a temporary mounting point for the SD card (say /new_home for example), and mount the partition on the newly created mounting point.
  2. Copy everything in you original /home to /new_home.
  3. Rename /home to something like /home_back to ensure you do keep the original data before everything is done.
  4. Create a new /home folder, which is where the partition on the SD card should be mounted.
  5. Unmount the SD card, and mount it again on /home.
  6. Modify /etc/fstab so your /home partition can be automatically mounted when booting up.
9

Hi Dave,

Looks like your solution would fit my needs but I don’t really know how to apply it… When I enter the system, my only choice is to use “nvidia” user, thus having mmcblk0p1 as root folder. Running lsblk doesn’t show any sda partition available.

My questions then are:

  • How can I access the sda partition?
  • Once logged on sda, how can I create a new Home directory and copy my current mmcblk0p1/home folder content to this new Home?
  • How can I then modify the fstab file to point to this new Home folder at power on?
  • How can I remove the mmcblk0p1 partition and reclaim its space to sda?

Not sure I’ve properly expressed my needs, I hope you get it… Basically, I want to get rid of this useless partition which has no sense for me: the SD card is only 64GB, I want to use it all!

Thanks in advance for any help!

PS: didn’t understand what the doc for flashing is actually describing… 🤔 Would this command copy the current mmcblk0p1 partition on another SDCard as sda1?

10

Hi Dave,

Sorry for the dumb questions but should these commands run from the card I want to modify? I just can’t see sda… Which partition are you referring to in point1: sda1 or mmcblk0p1?

The point is that mmcblk0p1 is now almost full and I can’t apply any software update… Why did Nvidia create this weird architecture?

Thanks in advance for any help!

11

Let’s make sure, the available options are that you either keep the internal eMMC as the root partition, and make your SD card the /home partition, or entirely re-flash so all the stuff lies in the SD card.

For the first option, currently both / and /home are on the eMMC, and you’d like to replace the /home with the partition on the SD card.

  • How can I access the sda partition?

Not sure why you cannot access the sda partition. Or you need to manually mount it?

  • Once logged on sda, how can I create a new Home directory and copy my current mmcblk0p1/home folder content to this new Home?

It’s not that you “logged on sda”, your root partition is now on the internal eMMC. You just make sure you can access sda, and copy everything in /home into it.

  • How can I then modify the fstab file to point to this new Home folder at power on?

There are a bunch of tutorials on the Internet teaching you how to modify this file, go Google for that.
I’m not gonna go step-by-step here.

  • How can I remove the mmcblk0p1 partition and reclaim its space to sda?

They live in different physical devices (SD card / eMMC), so you cannot “reclaim” the space, all you can do is either move the /home partition to the SD card, or do a clean re-flash so all the stuff is on the SD card. Also, the mmcblk0p1 on the eMMC is built directly in the machine, so you cannot remove it.

Sorry for the dumb questions but should these commands run from the card I want to modify? I just can’t see sda… Which partition are you referring to in point1: sda1 or mmcblk0p1?

As mentioned above, all the system stuff is on the mmcblk0p1 partiton.

12

Hi Dave,

Things are clearer now, thanks! Actually, the whole stuff is already installed on the SD card, so what I’d prefer is to boot directly on /sda1 and keep the eMMC partition for additional storage.

Currently booting on mmcblk0p1, here’s what sudo blkid returns:

/dev/loop1: SEC_TYPE="msdos" LABEL="L4T-README" UUID="1234-ABCD" TYPE="vfat"
/dev/mmcblk0: PTUUID="7c64b753-d268-449f-8097-e65a1e80262f" PTTYPE="gpt"
/dev/mmcblk0p1: UUID="414e8e89-46fb-4894-8152-be072e6ab742" TYPE="ext4" PARTLABEL="APP" PARTUUID="63dbd708-d4de-49eb-8dd7-0208f60f9910"
/dev/mmcblk0p2: PARTLABEL="DTB" PARTUUID="007c20cd-21ef-4647-8ccd-1a4e8fdc573c"
/dev/mmcblk0p3: PARTLABEL="TOS" PARTUUID="09cbe76a-5a2f-4f87-8051-9868ec1fef5c"
/dev/mmcblk0p4: PARTLABEL="EKS" PARTUUID="73313b0a-9d0b-4dbc-8632-364d950ad305"
/dev/mmcblk0p5: PARTLABEL="LNX" PARTUUID="6833949f-ac5c-402a-9cd3-4e0aa2d3a368"
/dev/mmcblk0p6: PARTLABEL="DTB-1" PARTUUID="27375cc8-cc54-4c53-b6c1-c229eaf04372"
/dev/mmcblk0p7: PARTLABEL="TOS-1" PARTUUID="1d98fdde-9382-421f-851d-8d2814150217"
/dev/mmcblk0p8: PARTLABEL="EKS-1" PARTUUID="064170ff-4cdc-476b-b002-610608481d6a"
/dev/mmcblk0p9: PARTLABEL="LNX-1" PARTUUID="215721ba-da3d-4e63-be57-b67a8742d321"
/dev/mmcblk0p10: PARTLABEL="BMP" PARTUUID="04aafc2d-25ca-48d1-971f-2b5e97e3760e"
/dev/mmcblk0p11: PARTLABEL="RP4" PARTUUID="58587ff9-7017-46c3-8303-666b04bb894b"
/dev/mmcblk0p12: PARTLABEL="recovery" PARTUUID="44800d22-35c9-489c-99c5-5c51c1a1b32c"
/dev/mmcblk0p13: PARTLABEL="recovery-dtb" PARTUUID="58c6e225-98f5-4bab-a375-5715ed3efe7f"
/dev/mmcblk0p14: PARTLABEL="kernel-bootctrl" PARTUUID="77ff654a-3759-4f1a-972f-427228639815"
/dev/mmcblk0p15: PARTLABEL="kernel-bootctrl_b" PARTUUID="4139cadb-4cdc-4acf-bc78-9a2cdb3b7b47"
/dev/mmcblk0p16: PARTLABEL="RECROOTFS" PARTUUID="123a99b9-7b2c-42fb-a383-983173bb9133"
/dev/mmcblk0p17: PARTLABEL="UDA" PARTUUID="415f556a-dbe1-4c4e-bbfd-645597510a46"
/dev/zram0: UUID="40443075-423e-4096-bc2c-09b10821f29e" TYPE="swap"
/dev/zram1: UUID="50704b05-1cb4-47c5-bcbb-58c9461d39ea" TYPE="swap"
/dev/zram2: UUID="20559c2e-ce73-4e54-8280-778dba45ea9c" TYPE="swap"
/dev/zram3: UUID="3805a776-9684-4d62-9d51-ed78549cb953" TYPE="swap"

As you can see, the SD card does not appear in the list. Any way to modify the “boot order”?

Thanks in advance for any help!

13

Hi, so your /home partition is now on the SD card right?
Unfortunately, AFAIK, without re-installing or re-flashing the whole system, you can only change where /home resides, not / (root), so I’d suggest you either keep the system as is, or start the whole process from the ground up, and make sure you install the system on the SD card.

14

Hi Dave,

I’m afraid the SD card is simply dead… 😉 I’ve tried to read it from another machine which cannot detect it either! Obvious conclusion… By the way, as I’ve read from another post, the board I’m using (Axiomtek) is not a dev board so I can’t expect it to boot as Nvidia’s devkit and I’ll probably have to keep the eMMC as the system partition and configure a (new) SD card as the /home partition and run my software from it.

This closes the case, so thanks a lot for your help!

15

You can often boot with an SD card as rootfs on a third party carrier board with eMMC module, but the manufacturer would have to provide the instructions. Note that an SD card on the module is quite different than an SD card on the carrier board. I’m not even sure if there is an eMMC model of Nano? In any case, the third party carrier board manufacturer would have the instructions for that if it is supported.

17

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