After upgrading of my e-mailbox running courier-imap-ssl, I discovered that connecting with Thunderbird just failed.

In /var/log/syslog:

imapd-ssl: couriertls: accept: error:14094417:SSL routines:SSL3_READ_BYTES:sslv3 alert illegal parameter

In Thunderbird, pressing CTRL+SHIFT+J shows the Thunderbird error console. It showed me information that something was wrong with some DH-parameter.

Following: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=787579, I generated a new keyfile using:

# export DH_BITS=2048 && mkdhparams

After generating a new “/etc/courier/dhparams.pem” and restarting courier-ssl by executing: /etc/init.d/courier-imap-ssl restart, I still could not connect with Thunderbird…

Then I discovered that in: /etc/courier/imapd-ssl, the parameter TLS_DHPARAMS could be set. I suspected that the pem-file for some reason could not be found by courier-imap-ssl. A bit strange of course, because it had never been a problem, until now.

So I added:

TLS_DHPARAMS=/etc/courier/dhparams.pem

After restarting courier-imap-ssl once again I discovered that this addition indeed solved my problem.

For future convenience I changed the BITS value in /usr/sbin/mkdhparams

from
BITS=768
to
BITS=2048

Its purpose is to keep the computer current with the latest security (and other) updates automatically. If you plan to use it, you should have some means to monitor your systems, such as installing the apt-listchanges package and configuring it to send you emails about updates. And there is always /var/log/dpkg.log, or the files in /var/log/unattended-upgrades. 

To install these packages, run the following command as root:

apt-get install unattended-upgrades apt-listchanges

To activate unattended-upgrades, you need to ensure that the apt configuration stub /etc/apt/apt.conf.d/50auto-upgrades contains at least the following lines: 

APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Unattended-Upgrade "1";

This file can be created manually or by running the following command as root:

dpkg-reconfigure -plow unattended-upgrades

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LC_CTYPE = “UTF-8”,
LANG = “en_US.UTF-8”
are supported and installed on your system.

Solution:

sudo dpkg-reconfigure locales

Choose: en_US.UTF-8
Then put:

LC_ALL=en_US.UTF-8

in /etc/environment

Log off and log on again

We will place “trim” scripts in four places:

/etc/rc.local = This will run at every boot  no matter what.
/etc/rc0.d/ = This will run at shutdown only.
/etc/rc6.d/ = This will run on restart only.
/etc/cron.hourly/ = This will run every hour the system is running.

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Useful after systemcrash:

When Mysql is not running:

 myisamchk –silent –force –fast –update-state /var/lib/mysql/bugs/*.MYI

myisamchk –safe-recover –force –sort_buffer_size=2G –key_buffer_size=2G /var/lib/mysql/*/*.MYI

-s, –silent option: Prints only errors. You can use two -s to make myisamchk very silent.
-f, –force option: Restart myisamchk automatically with repair option -r, if there are any errors in the table.
-F, –fast option: Check only tables that haven’t been closed properly.
-U –update-state option: Marks tables as crashed, when it finds any error.

When Mysql is running (which is kind of slow)

mysqlcheck –repair –all-databases

To switch of the autoverify feature on a 3ware controller which can be a real performance killer do the following:

From the console, enter the 3ware cli and first check the current status

tw_cli /c0/u0 show autoverify

/c0/u0 Auto Verify Policy = on

As you can see the autoverify feature is on Auto Verify Policy = on. If your raid controller is also c0 and you unit is u0 you may use the following command. Please check this first with the command:

tw_cli /c0 show

Do not just copy and paste. If c0 doesn’t work try a higher number it depends on which pci slot your controller is in.

tw_cli /c0/u0 set autoverify=off

Setting Auto-Verify Policy on /c0/u0 to [off] … Done.

Check the autoverify settings:

tw_cli /c0/u0 show autoverify

/c0/u0 Auto Verify Policy = off

That’s it no more autoverify. Please make sure to check you raid status regularly to detect problems.

Booting debian Linux on GPT disk
I tried to boot from newly installed 6 TB raidvolume. It showed me the grub2 prompt.
No big deal. I used some grub-commands to boot into the system and executed update-grub. Still after a reboot even a grub-rescue prompt appeared.
After booting into the system using grub-commands I ran: grub-install, which showed me this error:

/usr/sbin/grub-setup: warn: This GPT partition label has no BIOS Boot Partition; embedding won’t be possible!.
/usr/sbin/grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged..
/usr/sbin/grub-setup: error: if you really want blocklists, use –force.

Using parted I created a small partition (100 MB) at the end of the raid-volume, in my case partition 3. After this I executed in parted the command: set 3 bios_grub on. This enables the partition as a BIOS Boot partition.

Finally grub-install reported no errors. After rebooting the grub boot menu appeared again.