21 - Cluster Administration Tasks

Abstract

After cluster is built, certain administration tasks need to be implemented to ensure that the systems will operate smoothly. Some of these tasks deal with monitoring how the cluster behaves; others are more involved and relate to changing the behavior of the cluster. It's also just good to know the behavior of daemons that are the system administrator's friends. There is a nice Graphical User Interface (GUI) that the system administrator can use to monitor and manage the cluster. These types of tool are especially useful in a cluster because they present a picture and layout of the various cluster components, whether it is about hardware, file systems, or other cluster pieces. A system manager will frequently want to move the /tmp file system to either a drive local to a cluster member or to another disk to improve file system performance. Another reason to move/tmp is because a user could potentially fill up the root file system by writing to /tmp. Making it a separate file system eliminates that possibility. TruCluster Server (V5.1B) tools are included with the clustering software that automatically manage load balancing the Centralized File System (CFS) activity. The reason to try and balance the CFS activity is that if the member that's performing the I/O is not the CFS server, file system traffic has to go across the cluster interconnect, whether that's memory channel or Ethernet. On getting too many unfavorable combinations of cross-member Input/Output, or a single member with more than its fair share of CFS serving, it become possible to wind up with a performance problem. That doesn't mean that CFS is bad, but there is a tradeoff: a little performance for the sizable benefit of the Single System Image.