LifeKeeper for Linux Module 4: IP Recovery Kit

Transcription

1 LifeKeeper for Linux Module 4: IP Recovery Kit

2 Learning Objectives At the end of this module, you will understand: all aspects of the LifeKeeper for Linux IP Recovery Kit Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 2

3 Overview IP Recovery Kit Provides a mechanism to redirect client traffic from one server to another via an IP address that can be switched between servers Switchable IP Address A logical IP address that can be moved between servers Separate from the static IP address associated with the network interface card Applications under LifeKeeper protection are associated with the switchable IP address. If there is a failure on the primary server, the switchable IP address becomes associated with the backup server. Resource under LifeKeeper protection -- Switchable IP address Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 3

4 Overview Static IP Address: Static IP Address: LifeKeeper Cluster Switchable IP Address: / ` Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 4

5 IP Recovery Kit Setup Planning Considerations: Network Configuration Internal and external networks must be configured and working with the real IP addresses. Must decide if there are any externally advertised IP addresses suitable for LifeKeeper protection. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 5

6 IP Recovery Kit Setup Example: creating a switchable IP address for Initial Scenario: Web Server 1 Web Server Ending Scenario: Web Server 1 Web Server Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 6

7 IP Recovery Kit Setup Package Installation steeleye-lkip-<version>.noarch.rpm can be installed through GNOME RPM, rpm command line, or kpackage. Typically installed with other Core product packages Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 7

8 IP Recovery Kit Configuration Create a Resource Hierarchy 1. <Edit> <Server> <Create Resource Hierarchy> Select the IP Recovery Kit Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 8

9 IP Recovery Kit Configuration Create a Resource Hierarchy (cont.) 2. Select the Switchback Type -- Automatic or Intelligent Switchback type - dictates how the IP resource will be switched back to this server when it comes back into service after a failover or switchover. 3. Select the Primary Server for the IP resource. 4. Enter the IP address to be protected. 5. Select or Enter the network mask. 6. Select or Enter the Network Interface. 7. If using Local Recovery, select the Backup Interface. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 9

10 IP Recovery Kit Configuration Create a Resource Hierarchy (cont.) 8. Select or Enter a unique IP Resource Tag name. 9. Select the Source Address Setting. 10. Configure the Ping List. 11. Click on the Create button -- Create Resource Wizard will create the IP resource. Must extend resource in order to place it under LifeKeeper protection. Extend the IP Resource Goes through a similar wizard with input for a Target Server Also must provide a priority for the IP resource on the backup server. The primary server where the IP resource was initially created is given the default priority of 1. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 10

11 IP Recovery Kit Configuration Tasks GUI Resource Configuration Tasks In-Service Out-of-Service Extend a Resource Hierarchy Unextend a Resource Hierarchy Create Dependency Delete Dependency Delete a Resource Hierarchy Properties - View information about resource. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 11

12 IP Recovery Kit Other Features Ping List By default LifeKeeper uses a broadcast ping as a health check for an IP resource. In some cases, broadcast pings are not allowed. The Ping List provides a way to do health checks without broadcast pings. Addresses of routers or other network infrastructure devices are typically placed in the ping list. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 12

13 IP Recovery Kit Other Features Modify Source Address The Source Address Setting for an IP resource determines whether the switchable IP address should be used as the source address for outgoing traffic, when the IP resource is in-service. Default is NO Incoming request packets to the switchable IP address are responded to on the static IP address. The default setting is appropriate for the vast majority of situations. If changed to YES Incoming request packets to either the switchable or static IP address are responded to on the switchable IP address. When the IP resource is brought in-service, the TCP/IP routes on the system are modified so that all responses come from the switchable IP address. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 13

14 IP Recovery Kit Other Features Restore and Recover There are situations under which it is desirable to turn off all LifeKeeper actions for IP resources. Example: An IP resource needs to be extended to a system that is not on the local subnet. This is standard procedure in disaster recovery configurations. Typically used when replicating data (SteelEye Data Replication or Multi-Site Cluster) to a different subnet. The default setting is Enabled. When set to Disabled, the IP resource will be allowed to come inservice, but LifeKeeper actions for the resource are disabled. This is a node-specific property. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 14

15 IP Recovery Kit Switchover/Failover IP Switchover Manual Switchover initiated from the GUI through In-Service option. IP Recovery Kit removes the address from service on the active server and brings it in service to the backup server After the switchover, the IP resource has a different hardware address because it is now associated with a different LAN interface. Before users can reconnect, TCP/IP must determine the new address mapping. Recovery Kit takes care of this. IP Failover When the primary server fails, the IP Recovery Kit automatically brings the IP resource in-service on a backup server Note: Session context is lost in connection-oriented sessions such as telnet. In a failover case, a telnet session context is lost following recovery. The user must reconnect with a new telnet session. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 15

16 IP Local Recovery IP Local Recovery GOAL: Avoid failover by moving a protected IP address from the primary network interface to a backup interface within the same system. NOTE: Local Recovery is a feature of the IP Recovery kit and it works as advertised. However, SteelEye does not currently believe that Local IP Recovery is the best way to provide redundancy for Network hardware. NIC Bonding (or NIC teaming) is a better method today. IP Local Recovery is a feature that will be deprecated at some point. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 16

17 IP Local Recovery (cont.) Configuration Issues Backup interface must be attached to same physical network as primary interface Backup interface defined per system TCP/IP Subnets: If IP address being moved is on same subnet as other active IP addresses, the other IP addresses will be moved to their backup interface as well. Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 17

18 IP Local Recovery - Example Configuration Recommendations All LifeKeeper-protected IP addresses with a backup interface should be configured on their own logical subnet Multiple IP addresses configured on same subnet should share the same primary and backup interfaces 3 NICs (2 comm paths, 1 backup) Configuration Example Use LifeKeeper to protect two virtual IP addresses Configuration must support multiple comm paths Must provide a backup interface for the protected IP addresses Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 18

19 IP Local Recovery - Example NIC IP Address Subnet Net LK Priority eth Public Comm eth Private Comm eth n/a n/a n/a LK IP Interface Resource IP Address Subnet Net Primary Backup IP Public eth0 eth2 IP Public eth0 eth2 Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 19

20 IP Local Recovery - Example Private LAN Primary LK Heartbeat eth1 eth1 Backup Interface ( ) eth2 eth0 Primary Interface eth0 eth Secondary LK Heartbeat Public LAN Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 20

21 IP Local Recovery Backup Interface Manual Operations LKipbu utility command line only Add/Remove backup interface LKipbu [-d machine] {a r} t tag f inteface Move (manually) to backup interface LKipbu [-d machine] m t tag Query current primary and backup interface information LKipbu [-d machine] q t tag Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 21

22 Tuneable Parameters Values in /etc/default/lifekeeper Tunable Value NOBCASTPING NOIPUNIQUE IP_PINGTIME IP_PINGTRIES Explanation Broadcast ping used for checking health of IP resources 0 = Enable broadcast ping (Default) 1 = Disable broadcast ping Control check for IP address already active 0 = Keep IP uniqueness check (Default) 1 = Disable IP uniqueness check Time in seconds to wait for a ping reply during IP health checks Default = 1 Note: When using Ping List rather than broadcast ping, any value greater than 3 is ineffective. Number of ping retries performed during IP health check Default = 3 Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 22

23 Tuneable Parameters Values in /etc/default/lifekeeper Tunable Value IP_PINGPRELOAD IP_NOSAVEREPLY IP_NOLINKCHECK Explanation Number of ping packets preloaded on network during IP health check Default = 1 Disable saving of address that first responds to broadcast ping for use in subsequent IP health checks 0 = Enable address saving and use (Default) 1 = Disable address saving and use Disable link status check portion of IP health check 0 = Enable link status check (Default) 1 = Disable link status check Sep-10 Copyright by SteelEye Technology, Inc. All Rights Reserved World Wide. 23