Loading...

Indexing: Secondary Index Server

Table of Contents

Overview

Secondary Index Server is a feature of SnapProtect software that automatically creates a copy of an index onto another MediaAgent, called a secondary MediaAgent. The secondary MediaAgent is usually physically separate from the one on which the index was created. Having a copy of an index ensures that it remains available if the primary copy gets erased during a cleanup operation. Each Secondary Index Server can support multiple MediaAgents.

Note: Secondary Index Server is not supported by Indexing V2 MediaAgents.

Advantages of Secondary Index Server

Secondary Index Server ensures that operations relying on the index (such as browse, find and restore) are not delayed or prevented by an index being unavailable, or available only through a tape recall.

The Environment that a Secondary Index Server Benefits Most

This feature is primarily useful for setups that would otherwise rely on tape recalls when a primary index is no longer on the MediaAgent on which the index was created (the primary MediaAgent). It may have been aged off, or otherwise deleted from its primary MediaAgent.

Feature Requirements

Implementing the Secondary Index Server feature requires a MediaAgent to hold the copy of the index, which in most cases will be a separate MediaAgent. That secondary MediaAgent should have sufficient space in its Index Directory to hold indexes from all of the MediaAgents that it serves as secondary to. If the MediaAgent hosting Secondary Index Server is also serving as MediaAgent to clients of its own, it should have that space also.

Example:

  • MediaAgents MA1 and MA2 are backing up clients. Each has 500 GB of space in its Index Directory.
  • MediaAgents MA3 is backing up clients, and needs 500 GB for its own indexes.
  • If MediaAgent MA3 is deployed as the Secondary Index Server for MA1 and MA2, it should have 1.5 TB total space allocated to its Index Directory.

Configuring the Feature

Secondary Index Server is configured through two Additional Settings:

  1. The first setting is added to the MediaAgent that hosts the copy of the index. It designates the MediaAgent as a secondary index server.
  2. The second setting is added to the MediaAgent where the index gets created (the "primary" MediaAgent). It names the secondary MediaAgent.

The normal sequence is to configure a secondary MediaAgent first, then configure one or more primary MediaAgents to point to that secondary MediaAgent.

Configuration Settings

These are the two settings that control the operation of this feature:

Setting Name Platform Description Category Type Value
bISSECONDARYINDEXSERVER Secondary MediaAgent Makes the MediaAgent a Secondary Index Server. MediaAgent INTEGER 1
sSECONDARYINDEXSERVERNAME Primary MediaAgent The name of the secondary MediaAgent to which each index is copied after being created on the primary MediaAgent. MediaAgent STRING The client name of the secondary MediaAgent

Configuring the MediaAgents

  1. In the CommCell Browser, expand Storage Resources, then right-click the MediaAgent and click Properties.
  2. On the Additional Settings tab, click Add.
  3. In the Name box, enter the setting name, then press TAB.
  4. Verify that the values for Category and Type are the ones shown in the Configuration Settings table.
  5. In the Value box, enter the value shown in the Configuration Settings table.
  6. Verify that Enable is selected, then click OK in all open dialog boxes.
  7. On the primary MediaAgent computer, restart the NetApp Media Mount Manager service.

Feature Operation

During a backup job, an index is created on the MediaAgent through which the data is backed up. This MediaAgent copies completed indexes to the secondary MediaAgent, in the background, every 30 minutes. The end result is a copy of the index that can be used when the primary MediaAgent does not have it.

Secondary Index Retention and Cleanup

Index copies are saved in the CatalogServer folder, which is in the index directory. To ensure availability, the secondary copy of an index is subject to these retention rules:

  • Secondary indexes are not subject to event-based cleanup operations, but scheduled cleanups are performed on them. Aging for each index is determined by the retention rules set on the secondary MediaAgent. See Index Directory Cleanup
  • Setting a longer retention time on the secondary MediaAgent ensures that secondary indexes are kept longer than primary indexes are kept.

Operational Considerations

  • An index restore operation automatically copies the restored index to the secondary MediaAgent.
  • During browse, find or restore operations, if the required index is not present on the primary MediaAgent, the copy of the index is automatically downloaded from the secondary index server.
  • Indexes present on the primary MediaAgent at the time this feature is enabled are not uploaded to the secondary index server. Jobs running after this feature is enabled upload their indexes to secondary index server.
  • If the client name of the Secondary Index Server MediaAgent becomes changed (via the Client Properties dialog box for the secondary MediaAgent), the sSECONDARYINDEXSERVERNAME Additional Setting on each primary MediaAgent that uses that secondary MediaAgent must be updated with the new name, and the MediaAgent Services on those primary MediaAgents must be restarted.

FAQs

Does a backup job fail if the MediaAgent cannot access the secondary index server?

No, the backup does not fail. The index is copied to the secondary index server when the secondary MediaAgent becomes available again.

Can a MediaAgent use itself as a secondary index server?

Yes, but this removes some of the advantage of having a secondary copy. For example, the MediaAgent host computer may experience a hardware failure. If both copies of the index are on that one computer, both copies may be temporarily unavailable or even permanently lost. Also, having the index copied to a separate MediaAgent means it is subject to a different (normally longer) retention policy, giving more opportunity for recovery if needed.

Can the primary and secondary MediaAgents be hosted on different operating systems?

Yes. For example, a primary MediaAgent can be hosted on a Windows computer, while its designated secondary MediaAgent is hosted on a UNIX computer.