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RHEL / CentOS 7 Network Teaming

Below is an example on how to configure network teaming on RHEL/CentOS 7. It is assumed that you have at least two interface cards.

Show Current Network Interfaces [root@rhce-server ~]$ ip link 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state […]

unbound RHCE

This howto shows the steps needed to configure unbound for DNS caching and forwarding from the network. It assumes the server’s IP address is and is running RHEL/CentOS 7.

Installation [root@rhce-server ~]# yum install unbound

Configure Systemd [root@rhce-server ~]# systemctl enable unbound ln -s ‘/usr/lib/systemd/system/unbound.service’ ‘/etc/systemd/system/’ [root@rhce-server ~]# ^enable^start systemctl start unbound

Configure […]

Linux Disk Caching & Performance with vm.dirty_ratio & vm.dirty_background_ratio

we talked about how the memory on a Linux guest is used for the OS itself (the kernel, buffers, etc.), applications, and also for file cache. File caching is an important performance improvement, and read caching is a clear win in most cases, balanced against applications using the RAM directly. Write caching is trickier. The […]

Linux OS Tuning/Optimizations

High i/o wait tuning for File Servers

Under “Server”?“General” tab, change “Priority” configuration to “-19”. Process priority can be set from -19 to 20, -19 is the highest, 20 is the lowest.

Change to ‘deadline’ I/O scheduler

From command line (change the device ‘sda’ to appropriate device): echo “deadline” > /sys/block/sda/queue/scheduler kernel parameter, change /boot/grub/menu.lst, […]

Releasing cached memory in Linux && Set swappiness

Releasing cached memory in Linux

Under normal circumstances, modern Linux systems try to cache into memory disk data that is accessed often. Sometimes, we have that much memory in the system that our kernel keeps filling up the memory by caching every piece of data we access.

Other times, because of the swappiness factor, active […]

Kick start install CentOS 6.5 Install Problem Unable to read group information from repositories.

 CentOS 6.5 Install Problem// // //

CentOS 6.5 Install Problem I have recently installed CentOS 6.5 on a couple of computers, once without any problems and once with a fatal hang during install.  With both installs I chose to overwrite any existing partitions and use the whole hard-drive.The problem during the failed install happened […]

LVM volumes on CentOS / RHEL 7 with System Storage Manager

LVM volumes on CentOS / RHEL 7 with System Storage Manager

Logical Volume Manager (LVM) is an extremely flexible disk management scheme, allowing you to create and resize logical disk volumes off of multiple physical hard drives with no downtime. However, its powerful features come with the price of a somewhat steep learning curves, with […]


XFS File System

What is XFS?

XFS is a highly scalable, high-performance file journalling file system which was originally designed at Silicon Graphics, Inc in 1993. Originally XFS was used on Silicon Graphics Inc’s own operating system Irix, however, it was later ported to the Linux kernel in 2001. Today XFS is supported by most […]




CentOS installation configuration FTP server

CentOS install FTP server is configured under a simple procedure notes. client server

Installation yum install vsftpd

[root@server ~]# yum install -y vsftpd Loaded plugins: fastestmirror Setting up Install Process Loading mirror speeds from cached hostfile * base: * extras: * updates: Resolving Dependencies […]

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