Jetson nano clone SD card (For Jetpack 4.5.1)

 The actual size of SD card is different from each other. It will be problem when SD card image file size is large than target SD card.

sudo gunzip -c ~/dragon-eye.img.gz | sudo dd of=/dev/mmcblk0 bs=64k status=progress
62261100544 bytes (62 GB, 58 GiB) copied, 3227 s, 19.3 MB/s
dd: error writing '/dev/mmcblk0': No space left on device
146314+1607917 records in
146314+1607916 records out
62277025792 bytes (62 GB, 58 GiB) copied, 3266.33 s, 19.1 MB/s

Jetson nano will refuse to boot with this SD card. 

I found a procedure to fix the probelm

1.Shrink APP partition (ext4) before clone SD card to image file. Reserve 512MB space on tail.

2.Clone SD card to image file

sudo dd if=/dev/mmcblk0 conv=sync,noerror bs=64K status=progress | gzip -c > ~/dragon-eye.img.gz

[sudo] password for gigijoe: 

62306058240 bytes (62 GB, 58 GiB) copied, 1309 s, 47.6 MB/s

951808+0 records in

951808+0 records out

62377689088 bytes (62 GB, 58 GiB) copied, 1310.95 s, 47.6 MB/s

3.Copy image file to target SD card

sudo gunzip -c ~/dragon-eye.img.gz | sudo dd of=/dev/mmcblk0 bs=64k status=progress

[sudo] password for gigijoe: 

62261100544 bytes (62 GB, 58 GiB) copied, 3227 s, 19.3 MB/s

dd: error writing '/dev/mmcblk0': No space left on device

146314+1607917 records in

146314+1607916 records out

62277025792 bytes (62 GB, 58 GiB) copied, 3266.33 s, 19.1 MB/s

There's error of no space. It's ok, just ignore it.

4.Fix partition

This SD card is NOT ready to boot because the partition table is corrupt. Run gdisk and write back partition table to fix.

sudo gdisk /dev/mmcblk0 

GPT fdisk (gdisk) version 1.0.5

Warning! Disk size is smaller than the main header indicates! Loading

secondary header from the last sector of the disk! You should use 'v' to

verify disk integrity, and perhaps options on the experts' menu to repair

the disk.

Caution: invalid backup GPT header, but valid main header; regenerating

backup header from main header.

Warning! One or more CRCs don't match. You should repair the disk!

Main header: OK

Backup header: ERROR

Main partition table: OK

Backup partition table: ERROR

Partition table scan:

  MBR: protective

  BSD: not present

  APM: not present

  GPT: damaged

****************************************************************************

Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk

verification and recovery are STRONGLY recommended.

****************************************************************************

Command (? for help): p

Disk /dev/mmcblk0: 121634816 sectors, 58.0 GiB

Sector size (logical/physical): 512/512 bytes

Disk identifier (GUID): CEF61F19-EF34-40C6-B658-4039F0AB5630

Partition table holds up to 128 entries

Main partition table begins at sector 2 and ends at sector 33

First usable sector is 34, last usable sector is 121634782

Partitions will be aligned on 2048-sector boundaries

Total free space is 1079229 sectors (527.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name

   1           28672       120584191   57.5 GiB    8300  APP

Recovery/transformation command (? for help): w

Caution! Secondary header was placed beyond the disk's limits! Moving the

header, but other problems may occur!

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING

PARTITIONS!!

Do you want to proceed? (Y/N): y

OK; writing new GUID partition table (GPT) to /dev/mmcblk0.

The operation has completed successfully.

Now the SD card works ...