Monthly Archives: January 2020

RAID sync speed slow when installing Debian

I’m installing Debian on a computer where the rootfs will be stored on two 250GB NVMe drives that are RAIDed (RAID1) together. I couldn’t figure out a good way to also RAID (and add some redundancy to) the ESP partition, unfortunately, and I don’t think that’s possible – though it would be cool to have a working ESP partition, no matter which drive might fail. In the end, I followed this tutorial and RAIDed together two 249GB partitions I made on each on the drives – using the TUI (ncurses) interface of the Debian installer. Then, I decided to not install the system until mdadm would finish the sync, did Ctrl-Alt-F2 to switch to a terminal, then did cat /proc/mdstat – only to see 1000K/s speed and “30 hours left” estimate. Given that the drives were NVMe, this was very weird.

However, it seems like some settings in the Debian installer environment artificially limit the RAID sync speed to 1000K/s. Following this tutorial, I removed the limit using this command:

echo 1000000 > /proc/sys/dev/raid/speed_limit_max

Then, all went well and the array synced at full speed (1G/s in this case). Hope this helps you too!

‘python3 setup.py sdist bdist_wheel’ fail – possible fix

error: can't create or remove files in install directory
The following error occurred while trying to add or remove files in the installation directory:
[Errno 13] Permission denied: '/usr/local/lib/python3.6/dist-packages/test-easy-install-32566.write-test'
The installation directory you specified (via --install-dir, --prefix, or the distutils default setting) was: 
/usr/local/lib/python3.6/dist-packages/
Perhaps your account does not have write access to this directory? If the installation directory is a system-owned directory, you may need to sign in as the administrator or "root" account. If you do not have administrative access to this machine, you may wish to choose a different installation directory, preferably one that is listed in your PYTHONPATH environmentvariable. For information on other options, you may wish to consult the documentation at: https://setuptools.readthedocs.io/en/latest/easy_install.html Please make the appropriate changes for your system and try again.

You might want to update your setuptools – maybe also pip and so on:

sudo python3 -m pip install -U pip setuptools

That solved this for me.