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Administrator Help > Coveo Enterprise Search 7.0 > Administration Tool > Status Tab > Details Menu > Toggling the Index Between the Read-Write and Read-Only Modes

Toggling the Index Between the Read-Write and Read-Only Modes

The normal index mode is the read-write mode in which indexed documents are updated. The index can also be temporarily switched to the read-only mode to process all pending transactions and prevent further modifications to its content, but still enable queries to return results to end-users.

While the index is switching between modes, the Administration Tool pages are unavailable. In the read-only mode, the Administration Tool pages are available but you cannot change index parameter values.

Important: The index must be in the read-only mode while:

  • You back up, restore, relocate, or scan the index for virus (see CES and Anti-Virus Software).

  • If CES runs on a virtual machine, when you create a snapshot of the virtual machine.

The read-only mode ensures that:

  • No index files will change during the operation so that the backed up or relocated index is valid.

  • The operation does not disturb the index file deleting, renaming, or creation processes involved in the management of transactions so that the index remains and can restart in a valid state.


  • You can switch between read-write and read-only modes automatically following a schedule (see Modifying System Schedules). This is useful to ensure the index switches modes before and after your scheduled backup and virus scan processes (see CES and Anti-Virus Software).

  • The index automatically switches to the read-only mode to prevent errors when the index disk free space reaches a minimum of 5 GB, in which case an error message is logged. You can get an email notification when email alerts for fatal errors are configured (see Configuring Email Alerts).

  • You can force an index to start in read-only mode by adding the value name ForceReadOnly with empty data to the registry key [HKEY_LOCAL_MACHINE\SOFTWARE\Coveo\Enterprise Search\7\Instance\default]. The ForceReadOnly value is automatically deleted when you switch the index to the read-write mode. Forcing a read-only start can be useful for example when troubleshooting an issue where the index repeatedly crashes while in read-write mode. The ForceReadOnly feature is available with CES 7.0.6607+ (April 2014 monthly release).

To manually toggle between the read-write and read-only index modes

  1. On the Coveo server, access the Administration Tool (see Opening the Administration Tool).

  2. Navigate to the Details page (Status > Details).

  3. In the System State section, next to the Index is in [current_mode] mode status, click [Switch to Read-Only Mode] or [Switch to Read/Write Mode].

    Note: The time required to switch between modes increases with the number of active source crawlers and security providers, particularly when switching from read-write to read-only mode because they must all be stopped before switching.

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