Symptom: Suddenly found website access very slow, but server CPU, memory and disk usage are normal. Analysis and solution: Check /var/log/message logs and found records of ‘ip_conntrack table full dropping packet’. The kernel uses ip_conntrack…
High-Availability Redis Cluster Solution for NoSQL and Emergency Maintenance Tips: Assuming there is a master-slave setup, where the master has no persistence configured and the slave has AOF enabled. (The master handles backup and write services, while the slave handles read services.) Scenario: What should you do if the master suddenly goes down? www.2cto.com Solution: Connect to the slave and run a save operation …
I happened to notice that Hadoop’s system CPU usage was very high, and a quick search revealed this is actually a known issue. RHEL6 optimized memory allocation efficiency, which significantly improves KVM performance in certain scenarios: http://www.linux-kvm.org/wiki/images/9/9e/2010-forum-thp …
Bandwidth Limiting Commands for Huawei Switches and Cisco Switches: Huawei Switch: sys // Enter system
[LinkIDC-LF-J5]di cu // System
[LinkIDC-LF-J5]int e1/0/2 // Enter port
[LinkIDC-LF-J5-Ethernet1/0/2]int e1/0/3 // Change to port 3
[Link …
Applicable Models: All Servers Document Content: IBM RAID controllers can be categorized into three major types based on the hard drives they control: SCSI RAID controllers for SCSI drives: ServeRaid, ServeRaid II, ServeRaid 3L, ServeRaid 3H, ServeRaid 4L, ServeRaid 4Lx, …
1. What is downtime migration and how to avoid service unavailability caused by it. Cloud servers are deployed on physical machines. When the underlying physical machine experiences performance issues or other failures, the system initiates protective migration…
For hackers living in the post-PRISM era, times are tough. After Snowden exposed the NSA’s series of global surveillance programs, the free software community has been steadily developing effective countermeasures, and the Mempo project is one of them. The project’s goal is to provide the most secure desktop and ser…
This guide provides a step-by-step illustrated walkthrough for friends deploying Windows Server 2008 for the first time, hoping to help you improve your skills. The steps are as follows. 1 After inserting the Windows Server 2008 installation disc, restart the computer and set the BIOS boot order (note: set the BIOS boot order to boot from the CD-ROM), …
1. Boot from the CD/USB drive, select the option related to cracking the password, and confirm, as shown below:
2. There are two options here. If you’ve forgotten the password on your own computer, it’s recommended to select “Clear Windows Login Password.” After clearing the password, the password will be removed, and you can set a new one after entering the system. Select &l…
A server suddenly became inaccessible via Remote Desktop, even though port 3389 was open. It also could not be pinged, but after turning off its Windows Firewall, it could be pinged. It could still use Remote Desktop to connect to other servers. When a client tried to connect, it showed a message like “The connection was interrupted due to a network error…
