Raspberry pi best heatsink comparison benchmark

raspberry_pi_3_heatsinks

Raspberry Pi manufacturer have stated you don’t need heatsink for the normal operation of the Raspberry Pi device, however overclocked or heavily stressed devices will benefit from heatsink installation.
I decided to compare available heatsinks on the market and have found the best heatsink for Raspberry Pi 3.

First tested heatsink is small – 14x14x6mm, priced 1$ on Ebay
It has an adhesive layer for mounting on CPU.

raspberry_pi_small_heatsink

Second heatsink – is larger 50x25x10mm, also priced 1$

raspberry_pi_large_heatsink

Mounting was done with Arctic Silver thermal compound and и super-glue 🙂 Thermal compound was applied to the center and glue – to the corners of the chip.
Please note that this will be a permanent solution, and you will not be able to remove the heatsink.

For loading the CPU I used stress software (apt-get install stress).
Only 1 core of Raspberry Pi 3 was loaded – frequencies: arm_freq=1290 core_freq=430

Here are the temperature graphs:

raspberry_pi_temperature_heatsink

Red line – no heatsink.
Blue – small heatsink 14х14
Gren – large heatsink 50х25

For a price of 1$ you can greatly improve temperature of Raspberry Pi 3 – by 8 degrees in idle state and by 13 degrees under moderate load.

transaction check error – mysql-community-libs-compat conflicts with file from package compat-mysql51

While upgrading MySQL server on centos 6 from 5.5 to 5.7 you may encounter following error:

Transaction Check Error:
  file /usr/lib64/mysql/libmysqlclient.so.16.0.0 from install of mysql-community-libs-compat-5.7.11-1.el6.x86_64 conflicts with file from package compat-mysql51-5.1.54-1.el6.remi.x86_64
  file /usr/lib64/mysql/libmysqlclient_r.so.16.0.0 from install of mysql-community-libs-compat-5.7.11-1.el6.x86_64 conflicts with file from package compat-mysql51-5.1.54-1.el6.remi.x86_64

It can be resolved by running following yum transaction:

$ yum shell
> remove compat-mysql51
> install mysql-community-libs-compat
> run

This will update affected mysql libraries to newer version without breaking any dependencies.

Remove all store apps windows 10

windows_modern_apps_bloatware

If you don’t use new (modern / metro) style application in windows you can delete all of them with a single PowerShell command.
To open PowerShell: Right click on Windows logo -> Command Prompt (Administrator – type powershell and press Enter.

This command removes all store apps for currently logged in user.

Get-AppxPackage | Remove-AppxPackage

To delete installation packages from disk and prevent installation for new users:
WARNING! This cannot be undone, you will lose ability to install new apps from Windows Store.

Get-AppXProvisionedPackage -Online | Remove-AppxProvisionedPackage -Online

ISPconfig / dovecot – send mailbox quota warning to users

To alert users, that are approaching theirs mailbox quota limit you can use built in Dovecot plugin quota_warning.

1. Edit the main Dovecot configuration file:
/etc/dovecot/dovecot.conf

plugin {
  quota = dict:user::file:/var/vmail/%d/%n/.quotausage
  sieve=/var/vmail/%d/%n/.sieve

  # Do not change existing plugins defined above, just add new entries below

  quota_warning = storage=95%% quota-warning 95 %u
  quota_warning2 = storage=80%% quota-warning 80 %u
  quota_warning3 = -storage=100%% quota-warning below %u # user is no longer over quota
}

service quota-warning {
  executable = script /usr/local/bin/quota-warning.sh
  user = vmail
  unix_listener quota-warning {
        user = vmail
        mode = 0600
  }
}

This will execute defined script /usr/local/bin/quota-warning.sh when user will exceed 80 and 95% of their mailbox space.

2. Create the alerting script:

<code>
#!/bin/sh
PERCENT=$1
USER=$2
cat << EOF | /usr/libexec/dovecot/dovecot-lda -d $USER -o "plugin/quota=maildir:User quota:noenforcing"
From: postmaster@localhost.local
Subject: Mailbox size warning

Your mailbox is now $PERCENT% full. Please delete old messages.
EOF
</code>

You may edit the text to better explain required steps to resolve this issue.

OpenSSL check p12 expiration date

1. Check .p12 / .pfx certificate expiration date:

openssl pkcs12 -in testuser1.pfx -nokeys | openssl x509 -noout -enddate

To specify password in plain text, add -passin pass:”${pass}”

2. Export key and cert from .p12 / .pfx:

openssl pkcs12 -clcerts -nokeys -in myContainer.p12 -out usercert.pem
openssl pkcs12 -nocerts  -in myContainer.p12 -out userkey.pem

3. Connect to HTTPS server with client certificate:

openssl s_client -connect gmail.com:443 -cert usercert.pem -key userkey.pem