This is much better than using Perl,
grep, etc. for wandering through the code.
I purchased an Odroid-XU4 for ca. 80 EUR including power-supply and case from Pollin. The original manufacturer is hardkernel. I intended to use this small ARM computer as a router and firewall. In the past I had used routers from multiple vendors, e.g., Linksys/Cisco, TP-Link, AVM/FritzBox, Netgear, and so on. There is a rule of thumb with all these devices: Usually you have to reboot them once or twice a month, otherwise they misbehave somehow. At least three of these device went completely catatonic. Now I had enough of this, I also wanted a command line interface to the router, ideally a real Linux system with
gcc, etc. Although I already own an Intel NUC and I am very happy with this computer, an Intel NUC is a little bit too expensive to be used as just a router.
I recommend to additionally purchase a RTC backup battery. The Odroid has a realtime clock, but loses all date and time information once powered off. This way the log of the computer is garbled.
How fast can you wipe a complete disk? For this I dumped zeros to a MS Windows partition based on an SSD formatted with NTFS.
[root@i7 ~]# time dd if=/dev/zero of=/dev/sda1 bs=1M dd: error writing '/dev/sda1': No space left on device 81920+0 records in 81919+0 records out 85898297344 bytes (86 GB, 80 GiB) copied, 182.699 s, 470 MB/s real 3m2.703s user 0m0.033s sys 0m43.470s
It was a real pleasure to get rid of MS Windows after just 3 minutes 😉
Once more, second partition on SSD formatted with NTFS.
[root@i7 ~]# time dd if=/dev/zero of=/dev/sda2 bs=1M dd: error writing '/dev/sda2': No space left on device 147015+0 records in 147014+0 records out 154155352064 bytes (154 GB, 144 GiB) copied, 326.108 s, 473 MB/s real 5m26.110s user 0m0.097s sys 1m21.503s
In various forums one reads that one should use
dd to copy a ISO image to an USB stick. Although this works, more often you do not want to use a ISO image but rather copy a Linux system at hand. First you mount the root filesystem of the new USB stick, then mount /boot within a
chroot. Finally use
grub commands. I.e., type
mount /dev/sdc2 /mnt/stick arch-chroot /mnt/stick mount /dev/sdc1 /boot <--- /boot is local to chroot! grub-install --target=i386-pc --boot-directory=/boot /dev/sdc grub-mkconfig -o /boot/grub/grub.cfg umount /boot <--- umount "local" /boot
Setting the bootable flag in the partition table one either uses
gparted, a graphical tool, or, as the task at hand is so simple, one just uses
parted /dev/sdc set 1 boot on print
Unrelated, but often useful. Just in case you changed something in the initial RAM disk, use
mkinitcpio -p linux
1. I saved my data from SSD using
tar and saved tar-file on hard-disk:
cd / time tar cf /mnt/c/home/klm/ssd1.tar bin boot etc home opt root srv usr var
Alternatively one can use
cp -a to copy directories with symbolic links. Option
-a is the same as
2. I used
gparted to partition the SSD, creating
/ (root). For
/boot I directly enabled btrfs in
3. Encrypt the partition.
cryptsetup -y -v -s 512 luksFormat /dev/sdc2
Then open it and give it an arbitrary name:
cryptsetup luksOpen /dev/sdc2 cryptssd
4. Create filesystem using btrfs. This is the reason for all this effort. Although this is the easiest.
/etc/fstab, e.g., with
genfstab -U /mnt >> /mnt/etc/fstab
UUID=3b8bb70c-390a-4a9e-9245-ea19af509282 / btrfs rw,relatime 0 0 UUID=a8d6c185-0769-4ec5-9088-2c7087815346 /boot ext4 rw,data=ordered,relatime 0 2
Check results with
6. Chroot into new system using
arch-chroot and put GRUB on it, as usual. Add required directories, first.
mkdir boot proc run sys tmp
Then edit the configuraton file for GRUB:
vi /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="cryptdevice=UUID=5a74247e-75e8-4c05-89a7-66454f96f974:cryptssd:allow-discards root=/dev/mapper/cryptssd" grub-install --target=i386-pc /dev/sdb grub-mkconfig -o /boot/grub/grub.cfg
:allow-discards after cryptssd is for SSD TRIM. For a mechanical hard drive this keyword should be omitted.
7. Install btrfs utilities and programs on new system if not already installed. Add the btrfs executable to the initial RAM disk, i.e., set the entry for
pacman -S btrfs-progs vi /etc/mkinitcpio.conf . . . BINARIES="/usr/bin/btrfs" . . . mkinitcpio -p linux
8. Extracting back from the tar-file.
time tar xf /mnt/c/home/klm/ssd1.tar
9. Adding TRIM for SSD:
systemctl status fstrim systemctl enable fstrim.timer systemctl start fstrim.timer
Show timers (like crontab -l):
10. A simple benchmark, as indicated by above
tar, does not show any performance benefits so far. But performance was not the main motivator, but rather the added functionality, especially taking snapshots.
Just upgraded PulseAudio from 9.0-1 => 10.0-2, which was no good, as I was left with no sound.
downgrade.sh libpulse pulseaudio pulseaudio-bluetooth
From now on I have to use
pacman -Syu --ignore pulseaudio --ignore libpulse --ignore pulseaudio-bluetooth
to not lose the good version and getting the infected version again.
After upgrading to version 16.05.7-1 I noticed the following: If
slurmd is started by
systemd then the pid-file specified for
PIDFile) should match the pid-file location (
SlurmdPidFile) given in
By the way, if one gets an error
slurm_receive_msg: Zero Bytes were transmitted or received
check your date and time of your nodes.