InfoScale™ 9.0 Cluster Server Agent for Hitachi TrueCopy/HP-XP Continuous Access Configuration Guide - Windows

Last Published:
Product(s): InfoScale & Storage Foundation (9.0)
Platform: Windows
  1. Introducing the agent for Hitachi TrueCopy/Hewlett-Packard XP Continuous Access
    1.  
      About the agent for Hitachi TrueCopy/HP-XP Continuous Access
    2.  
      Supported software
    3.  
      Supported hardware
    4.  
      Typical Hitachi TrueCopy/Hewlett-Packard XP Continuous Access setup in a VCS cluster
    5. Hitachi TrueCopy/Hewlett-Packard XP Continuous Access agent functions
      1.  
        About the Hitachi TrueCopy/Hewlett-Packard XP Continuous Access agent's online function
  2. Configuring the agent for Hitachi TrueCopy/Hewlett-Packard XP Continuous Access
    1. Configuration concepts for the Hitachi TrueCopy/Hewlett-Packard XP Continuous Access agent
      1.  
        Resource type definition for the Hitachi TrueCopy agent
      2. Attribute definitions for the TrueCopy/HP-XP-CA agent
        1. About the SplitTakeover attribute for the Hitachi TrueCopy agent
          1.  
            SplitTakeover attribute = 0
          2.  
            SplitTakeover attribute = 1
        2. About the FreezeSecondaryOnSplit attribute for the Hitachi TrueCopy agent
          1.  
            FreezeSecondaryOnSplit attribute = 0
        3.  
          About the HTC configuration parameters
        4.  
          Special consideration for fence level NEVER
        5.  
          Considerations for calculating the AllowAutoFailoverInterval attribute value
      3.  
        Sample configuration for the TrueCopy/HP-XP-CA agent
    2. Before you configure the agent for Hitachi TrueCopy/Hewlett-Packard XP Continuous Access
      1.  
        About cluster heartbeats
      2.  
        About configuring system zones in replicated data clusters
      3.  
        About preventing split-brain
    3. Configuring the agent for Hitachi TrueCopy/Hewlett-Packard XP Continuous Access
      1.  
        Configuring the agent manually in a global cluster
      2.  
        Configuring the agent manually in a replicated data cluster
  3. Testing VCS disaster recovery support with Hitachi TrueCopy/Hewlett-Packard XP Continuous Access
    1. How VCS recovers from various disasters in an HA/DR setup with Hitachi TrueCopy/Hewlett-Packard XP Continuous Access
      1.  
        Failure scenarios in global clusters
      2.  
        Failure scenarios in replicated data clusters
      3.  
        Replication link / Application failure scenarios
    2.  
      Testing the global service group migration
    3.  
      Testing disaster recovery after host failure
    4.  
      Testing disaster recovery after site failure
    5.  
      Performing failback after a node failure or an application failure
    6.  
      Performing failback after a site failure
  4. Setting up fire drill
    1.  
      About fire drills
    2. About the HTCSnap agent
      1.  
        HTCSnap agent functions
      2.  
        Resource type definition for the HTCSnap agent
      3.  
        Attribute definitions for the HTCSnap agent
      4.  
        About the Snapshot attributes
      5.  
        Sample configuration for a fire drill service group
    3.  
      Additional considerations for running a fire drill
    4.  
      Before you configure the fire drill service group
    5. Configuring the fire drill service group
      1.  
        About the Fire Drill wizard
    6.  
      Verifying a successful fire drill

Considerations for calculating the AllowAutoFailoverInterval attribute value

You can configure the VCS agent for HTC to trigger an automatic failover when a primary site failure occurs in a Global Cluster Option (GCO) environment. Such a configuration comes into effect after a certain time has elapsed, which is defined by the AllowAutoFailoverInterval attribute.

The value of AllowAutoFailoverInterval is determined based on the following events:

  • The time when the latest PAIR status of P-VOL is propagated to the secondary site

  • The time when the secondary site detects the primary site failure

  • The time when the remote RAID manager is longer reachable

Table: Variables used to calculate the value of AllowAutoFailoverInterval

Variable

Source

Default value

Usage

A = MonitorInterval attribute value

HTC agent

60 seconds

Specifies how frequently the agent polls and records the PAIR status for P-VOL.

B = AYAInterval attribute value

Heartbeat agent

60 seconds

The interval between two heartbeats in the global cluster. You can modify this value using the hahb command, for example:

hahb -modify ICMP AYAInterval 45

C = AYARetryLimit attribute value

Heartbeat agent

3 attempts

The maximum number of lost heartbeats before the agent reports that heartbeat to the cluster is down. You can modify this value using the hahb command, for example:

hahb -modify ICMP AYARetryLimit 2

D = Timeout value specified for the cluster node at the Primary site

HORCM file at the Secondary site

120 seconds

The HTC agent at secondary site attempts to get the replication link state using the pairdisplay command. This operation times out after the specified interval.

Considering the default values, the time interval is calculated as follows:

A + (B x C) + D + BufferTime 
= 60 + (60 x 3) + 120 + 40 
= 400 seconds

You can modify these attribute values (A to D) to reduce the effective failover time. For example, the turnaround time can be reduced to 180 seconds by tweaking the attributes values as follows:

  • A = 30 seconds

  • B = 45 seconds

  • C = 2 attempts

  • D = 30 seconds

Caution:

AYAInterval and AYARetryLimit are responsible for GCO link monitoring and toleration of intermittent network failures. Significantly reducing this value may falsely flag intermittent network issues as network failures, which may trigger a failover.

Note:

AYAInterval and AYARetryLimit are not used in a replicated data cluster (RDC) environment, so the effective time for failover in that environment is greatly reduced.