Reinstallation of TrueNAS fails - Error can't find partition 2 on mmcblk0

[drcjb]

Dear All,

My first post here, so hope I am in the right place?

I installed TrueNAS 25.04.01 last week on my new Beelink ME Mini with 24TB of NvME SSDs. All went very well and I was operational within hours and tested my wife’s iPad’s access to a .iso file on the NAS.

Then i did something stupid and managed to block all SMB access to the device. Tried to fix the problem but to no avail.

So I thought as I had done much in the way of configuring or installing my iso library I decided just to reinstall TrueNAS from the USB stick I had used for the first installation.

It starts up ok, I select the internal memory of the device and I enter the admin password, and almost immediately I get the message that the installer can’t find partition 2 on the SSD disk?

Why would it work the first time but not the second? The device comes with Windows installed on it which I overwrote with TrueNAS and that worked, but trying to reinstall TrueNAS over TrueNAS fails?

Any help or ideas gratfully received.

Best regards, Colin

[oxyde]

Before proceed make sure to wipe your boot disk, you can do It also during installation: choose to open the shell → use lsblk to identify the correct disk (take care don’t wipe something else ) → then use blkdiscard /dev/sd* -f → retry installation

[drcjb]

Many thanks for your rapid reply oxyde. I used blkdiscard /dev/mmcblk0 it did not like the * for the 3 partitions. That seemed to do something but the install still gave “Failed to find partition number 2 on mmcblk0” even though lsblk clearly shows the 3 partitions.

[drcjb]

It didn’t like the -f parameter even before the drive reference.

[oxyde]

@drcjb

blkdiscard /dev/mmcblk0

Realizing now that your disk Is an emmc, i think that the command did nothing and not fit your case.

When you used lsblk you see if those partition were read only?

I think that bitting the bullet and use a dd will erase the partition table, but wait a second opinion maybe there Is a fastest way

[drcjb]

I have a photo of the lsblk output but I can’t upload it, is there any way.

[drcjb]

Here is the OCR version…

root@truenas-installer:/# lsblk
NAME          MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
loop0           7:0    0  217M  1 loop /usr/lib/live/mount/rootfs/filesystem.squashfs
                                            /run/live/rootfs/filesystem.squashfs
sda             8:0    1 29.8G  0 disk
├─sda1          8:1    1  122K  0 part
├─sda2          8:2    1    5M  0 part
├─sda3          8:3    1  1.8G  0 part /cdrom
└─sda4          8:4    1  300K  0 part
mmcblk0       179:0    0 58.2G  0 disk
├─mmcblk0p1   179:1    0    1M  0 part
├─mmcblk0p2   179:2    0  512M  0 part
└─mmcblk0p3   179:3    0 57.7G  0 part
nvme0n1       259:0    0  3.6T  0 disk
└─nvme0n1p1   259:1    0  3.6T  0 part
nvme0n1       259:0    0  3.6T  0 disk
nvme1n1       259:2    0  3.6T  0 disk
└─nvme1n1p1   259:3    0  3.6T  0 part
nvme2n1       259:4    0  3.6T  0 disk
└─nvme2n1p1   259:5    0  3.6T  0 part
nvme4n1       259:6    0  3.6T  0 disk
└─nvme4n1p1   259:7    0  3.6T  0 part
nvme5n1       259:8    0  3.6T  0 disk
└─nvme5n1p1   259:9    0  3.6T  0 part
mmcblk0boot0  179:256  0    4M  1 disk
mmcblk0boot1  179:512  0    4M  1 disk

[oxyde]

@drcjb

mmcblk0boot0  179:256  0    4M  1 disk
mmcblk0boot1  179:512  0    4M  1 disk

Try the commands - reboot explained here

Ugreen DXP2800 25.04RC1 emmc install

Stumbled on the same error during installation of TrueNAS 25.04 on GMKTec NucBox G9 NAS. It turned out that the error was due to the boot partitions mmcblk0boot0 and mmcblk0boot1 switched into read-only mode. I fixed the issue by following the recipe in kernel org note mmc-dev-parts.txt In the boot menu select shell List your block devices $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS ... mmcblk0 179:0 0 58.2G 0 disk ├─mmcblk0p1 179:1 0 1M 0 part ├─mmcblk0p2 …

$ echo 0 > /sys/block/mmcblk0boot0/force_ro
$ echo 0 > /sys/block/mmcblk0boot1/force_ro

Also in the same topic people talks about wiping with dd, so on that not seems i was wrong in case try It

[drcjb]

Many thanks for this information Davide, I have done the following:

1: Start up ME Mini with USB stick containing .iso of TrueNAS 25.4.0
The installation starts and run up to the 4 choice menu.

2: I select Shell and use the lsblk and echo commands to make the two boot partitions RW. That works just fine.

3: I exit thhe shell and select the installation option. It starts running and almost immediately stops with the same error can’t find partion 2 on mmcblk0.

4: I hit Enter and return to the 4 choice menu.

5: I select shell and run lsblk, which shows that the two boot partions are still RW.

Please can yuo explain your DD option (destroy disk?).

[drcjb]

I just reread the instructions from the post you linked to and is says restart the system and then reinstall TrueNAS.

So I just did a shutdown and restart but when I get the shell the two boot partitions are back to RO!

I try to see if there is anything in the BIOS that forces that change.

[drcjb]

I have send a support request to the manufacturer, I did upgrade the BIOS but that made no change at all to this problem.

[oxyde]

I think that the last thing you can try Is to wipe the disk with the dd command.

The Complete Guide to the dd Command in Linux

Here you find some explanation (go to the Wiping a Block Device section), but Is also mentioned in the thread above.

Otherwise, i have no more idea, i have poor experience with device like yours

[drcjb]

Dear All,

By installing TrueNAS 24.04 and upgrading to 25.04 my ME Mini is now operational. I reviewed all the threads Davide sent including

Installation failed on eMMC Odroid H4+

which includes comments about my hardware and decided before plunging in modifying Python code in the installer I would try the 24.04 install and it worked. I have now upgraded to 25.04 and have restarted my configuration.

I have learnt a lot about emmc chips and their challenges!

Many thanks to Davide for your kind assistance and patience!

Best regards, Colin

[CursorBeat]

In my case it helped to retry it again and again without restart - after 8-10 times it worked and installed correctly with Verison TrueNAS Scale 25.04.2.1.

Got the hint from here: How to I wipe the eMMC - Beelink Forum and it`s a working solution.

[borja]

I found a different solution, as retry did not work for me.
I just gave the install script a bit more time to get the right data from the system.
Just open a shell and run:

sed -i s/tries=30/tries=130/ /usr/lib/python3/dist-packages/truenas_installer/install.py

Then go back to run the installer.

[davedevos]

I can confirm that this solution worked for me on a LincStation N2, thank you!

[geerlingguy]

@borja

sed -i s/tries=30/tries=130/ /usr/lib/python3/dist-packages/truenas_installer/install.py

Also confirming that running exactly:

sed -i s/tries=30/tries=130/ /usr/lib/python3/dist-packages/truenas_installer/install.py

On a LincStation N2 fixed the same problem. After running that command in the Shell, type exit and then go right back into the installer.

[toji_fushiguro]

Worked for me as well!

[Eldho_Varghese]

Hi Geeks,

Just wanted confirm, there are 2x4MB disks showing up as mmcblk0boot0 and mmcblk0boot1. Is that normal when using eMMC disk as the boot drive ? Or is there any way to remove it. I have seen some suggestions to making it RW and dd’ing to Zero. Is that necessary? Even after doing that That showed up after installation. So just ignore and live with it ?

[Bob_Hyman]

Easiest workaround here is to hack install script rather than try to alter mmcblk0boot0.
I have a beelink me mini, and am installing 25.10, ran into same error, hacked tries to 130, but then ran into a second error, zpool create failing on partition 3. So I changed it to 200, and that worked FTW.