The application of DRBD in Linux-HA Haibo Zhang 4/28/2014

What is DRBD? DRBD (Distributed Replicated Block Device) is a software development for high availability clusters

What is the HA? The Linux-HA (High-Availability Linux project provides a high availability (clustering) Solution for Linux, FreeBSD, OpenBSD, Solaris and which promotes reliability, availability, and serviceability (RAS).

Easy way to understand Disk Array RAID （ Redundant Arrays of Inexpensive Disks ， RAID ）

The structure of HA

DRBD core functionality by Linux kernel implements, Under the file system it is closest to the IO stack. Conducive to the transmission of the data System should be the shared disk file system like GFS2 ； OCFS2

How the DRBD running Mirroring of important data Fully synchronous switch between master slave

File transfer The local write return immediately successful and the data is sent to the other party, dual both power-down, the data may be lost Local and the other write successfully identified and returned. Dual power-down or also damaged disk, the data may be lost Return immediately write local success, the data on buffer. may be lost Copy data Asynchronous Memory synchronization

heartbeat

Split brain Each node want to switch to master node when the net broken Quorum Algorithm to handle split brain

Core of the progress Input data heartbeat Copy data Receive Data respond Transfer data to node Input data heartbeat Copy data

DRBD in the in reality Company with big data Bank Database system

Tha Thank You!