| Red Hat Docs > Manuals > Red Hat High Availability Server Manuals > |
|
| Red Hat Linux 6.2: The Official Red Hat High Availability Server Installation Guide | ||
|---|---|---|
| Prev | Chapter 8. Linux Virtual Server (LVS) | Next |
During configuration, you select the tool family (either rsh or ssh) that will be used to synchronize the /etc/lvs.cf configuration files on the LVS routers. This tool will also be used for parts of the data gathering used in determining proper load balancing. The selected tool must be enabled on the LVS routers, such that the root account on each router can log in to the other router without administrator intervention.
Also during configuration, you select the tool (uptime, ruptime, or rup) that the active router will use to monitor the workload on the real servers. Enable the selected tool on the real servers. If this cannot be done (for example, one of your real servers is a Windows/NT Web server), the cluster will still provide highly available services. However, the weighted round robin and weighted least-connections algorithms (described in Table 8-1 will be affected. Namely, since load information will not be available, the user-assigned weights will be applied statically, rather than being dynamically adjusted based on server workload.
Table 8-2 describes in general terms the steps required to enable these tools on the source and destination hosts. For more detailed information, see the appropriate man page(s). Note that, with rsh and ssh, the root account must be able to log in over the network. To enable remote root login to a Red Hat Linux system, remove the following line from the file /etc/pam.d/login:
auth required /lib/security/pam_security.so
|
This is a security hole, albeit small. Make sure you have the LVS nodes properly firewalled so that logins are allowed only from trusted sources.
Table 8-2. Enabling Synchronization and Monitoring Tools
| Tool | Do This |
|---|---|
| rsh | Create a .rhosts file with permission 600 in the root account's home directory (/root) on the destination host. There should be a line in the file naming the source host and user (for example, foo.host1.com root). |
| ssh | Obtain/install the tool (which for legal reasons cannot be released with international Linux distributions). On the source and destination hosts, disable remote login via all other methods, set up RSA-based authentication using .ssh/authorized_keys, and start sshd. |
| uptime | On each real server, enable either rsh or ssh, as described above. |
| ruptime | Set up each LVS router and real server to start rwhod whenever it boots. |
| rup | Set up each real server to start rpc.rstatd whenever it boots. |
 | Please Note |
|---|---|
The rup and ruptime programs require that the rstatd and rwhod daemons run on the system. Use one of the several available tools (such as chkconfig to enable these daemons. |