Do I have to unmount /dev/mmcblk0 when doing dd over SSH? - backup

I am using this command to back up my 4 GB MMC card on BeagleBone Black which is running Ångström Linux:
beaglebone:/# dd if=/dev/mmcblk0 | ssh admin#192.168.1.123 "dd of=/volume1/homes/admin/test.img"
It seems to be working great. But I'm wondering, do I need to unmount the SD card? What if things change the SD card during the backup? How do I avoid this or avoid getting a corrupt image?

If you mount the SD card in read only no, you don't need to umount it.
But if it is mounted RW, in case you make even one operation you're very likely to get an inconsistent filesystem.
So either you umount it or you remount it in RO.

Related

Qnx-neutrino can't format my partitions with fdisc, process freezes

I'm trying to format my HDD 250Gb in QNX-neutrino OS running on Oracle VM in Windows 10. I mounted my HDD and everything looks fine. I run command
fdisk /dev/hd1
And create 4 partitions with next sizes:
1325, 124684, 17265, 47496 MB
After that I run command:
mount -e /dev/hd1
And when I tried to format created partitions with commands:
mkqnx6fs –q –b4096 /dev/hd1t177
mkqnx6fs –q –b4096 /dev/hd1t178
mkqnx6fs –q –b4096 /dev/hd1t179
mkqnx6fs –q –b4096 /dev/hd1t180
the process starts and never end. Terminal is just frezees. What can I do to fix it? Or there is another way to format my partitions in this system?
I had the same issue when used VM Oracle after markup my HDD. Then I tried VM Ware and this issue was resolved.
VM Ware didn't suit me, because it counted cylinders incorrectly.
I find the solution. The problem was due to poor contact of the USB cable with my hard drive. I tried changing the usb cable and usb port and it worked fine.

Why is fdisk -l showing different results for the same vdi virtual drive when different virtual machines are used in VirtualBox

VirtualBox (Version 5.2.24 r128163 (Qt5.6.2)) user with xubuntu guest (Ubuntu 18.04.2 LTS) and Windows 10 host here.
I recently tried to resize my vdi from ~100GB to 200GB. In windows I used the command:
./VBoxManage modifyhd "D:\xub2\xub2.vdi" --resize 200000
That went fine. Then I used a gparted live cd to create a vm, attached the vdi and resize the partitions:
gparted gui
All looks good. If I then use the 'fdisk -l' command whilst in the gparted vm the increased partition sizes are visible as expected.
fdisk -l results for vdi attached to gparted vm
If I try and resize the file system for one of the newly resized logical drives with 'resize2fs /dev/sda5' I am told it is already 46265856 blocks long and there is nothing to do.
However....
If I then re-attach this vdi to an ubuntu vm and boot up with the vdi, the 'fdisk -l' command gives different results and is basically telling me that the drive is still 100GB in size.
fdisk -l results for the same vdi attached to ubuntu vm
The 'df' command confirms that it is not resized.
df command output with same vdi attached to ubuntu vm
If I try the command 'resize2fs /dev/sda5' I get the result:
The filesystem is already 22003712 (4k) blocks long. Nothing to do!
How can I fix this and make the ubuntu vm see that the disk and partitions have been increase in size?
Ok. I will answer my own question (thank you for the negative vote anonymous internet).
This issue occurs when you have existing snapshots of the drive that you are trying to expand associated with a VirtualBox VM.
I found this described in VirtualBox's documentation.
https://forums.virtualbox.org/viewtopic.php?f=35&t=50661
One suggested solution is to delete the snapshots, however I got an error message when I attempted that.
The solution that worked for me was to clone my VM. The cloned VM (which did not have any snapshots associated with it), behaved as expected and showed the correct size for the resized disk.
To be clear: the situation I described above is 100% true.
Hope that helps someone.

install proxmox from usb device error

I try to install Proxmox using a USB, and when I click to install, I see the next error:
testing cdrom /dev/sr0
umount: can't umount /mnt: Invalid argument
testing again in 5 seconds
Finally:
no cdrom found - unable to continue (type exit or CTRL-D to reboot)
I prepare the USB using ImageUSB in Windows, and it does have the previous fail, then I try to prepare in Ubuntu using dd if=pve-cd.iso of=/dev/XYZ bs=1M, I don't know where is the problem.
For someone out there still having similar issue, use below method to create the installation media. That should help.
Instructions for Windows
Download Etcher from https://etcher.io , select the ISO and your USB Drive.
If this doesn’t work, alternatively use the OSForensics USB installer from http://www.osforensics.com/portability.html
Instructions for GNU/Linux
You can simply use dd on UNIX like systems. First download the ISO image, then plug in the USB stick. You need to find out what device name gets assigned to the USB stick (see below). Then run:
dd if=proxmox-ve_*.iso of=/dev/XYZ bs=1M
Note: Be sure to replace /dev/XYZ with the correct device name.
Caution: Be very careful, and do not overwrite the hard disk!
Instructions from: https://pve.proxmox.com/wiki/Install_from_USB_Stick

How to install linux on odroid-U3(or other odroid version)?

I have an odroid-U3, and I don't know how to install a linux on it, can anyone tell me how to do it? and I have another question, can odroid-U3 powered by USB port?
Grab the appropriate linux distro from:
http://os.archlinuxarm.org/os/
or follow the steps below which will use the U2 image which is the same for U3:
SD Card Creation
Replace sdX in the following instructions with the device name for the SD card as it appears on your computer.
Zero the beginning of the SD card:
dd if=/dev/zero of=/dev/sdX bs=1M count=8
Start fdisk to partition the SD card:
fdisk /dev/sdX
At the fdisk prompt, create the new partitions:
Type o. This will clear out any partitions on the drive.
Type p to list partitions. There should be no partitions left.
Type n, then p for primary, 1 for the first partition on the drive, and enter twice to accept the default starting and ending sectors.
Write the partition table and exit by typing w.
Create and mount the ext4 filesystem:
mkfs.ext4 /dev/sdX1
mkdir root
mount /dev/sdX1 root
Download and extract the root filesystem (as root, not via sudo):
wget http://archlinuxarm.org/os/ArchLinuxARM-odroid-u2-latest.tar.gz
bsdtar -xpf ArchLinuxARM-odroid-u2-latest.tar.gz -C root
Flash the bootloader files:
cd root/boot
./sd_fusing.sh /dev/sdX
cd ../..
Unmount the partition:
umount root
Insert the SD card into the board, connect ethernet, and apply 5V power.
Use the serial console (with a null-modem adapter if needed) or SSH to the IP address given to the board by your router.
Login as the default user alarm with the password alarm.
The default root password is root.
eMMC Module Creation
Attach the eMMC module to the micro SD adapter, and plug that into your computer.
Follow the above steps to install Arch Linux ARM, and boot the board with the eMMC still attached to micro SD adapter, plugged into the SD slot in the board.
Re-flash the bootloader to the protected boot area of the eMMC module:
cd /boot
./sd_fusing.sh /dev/mmcblk0
Power off the board:
poweroff
Remove the micro SD adapter, detach the eMMC module, and connect the eMMC module to its connector on the board.
Re-apply power the board.
Use the serial console (with a null-modem adapter if needed) or SSH to the IP address given to the board by your router.
Login as the default user alarm with the password alarm.
The default root password is root.
You can follow the official guide at archlinuxarm.org/platforms/armv7/samsung/odroid-u3
Note: If you stuck at step 7 when performed
cd root/boot
./sd_fusing.sh /dev/sdX
cd ../..
you can open the file sd_fusing.sh, change the line
#!/usr/bin/bash
into
#!/bin/bash

Yosemite: How to remove files in /.Trashes on a TC external disk?

I have extended my Time Capsule storage by adding an external disk to the TC USB port. Everything looks good except I see that /.Trashes on this disk has 241 GB of data that I don't need. How can I get rid of it?
I am comfortable using terminal and sudo, although I'm very rusty, but I have no clue of even how to access this TC external disk from terminal.
I figured out how to do it. All external disks appear under /Volumes in terminal. I cd'd to the directory under there that held my 241 GB of unwanted data and used
rm -r *
to remove all of it. Of course this "remove recursively" should be used with great caution.