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StorageTek SL3000 User's Guide E20875-05 |
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# 7 Redundant Electronics

The optional redundant electronics (RE) feature provides failover protection for the library controller. This allows an Oracle support representative to replace the faulty card while the library is online and provides minimal disruption during firmware upgrades.

Note: Any reference to the HBC card also refers to the HBCR card.

## Requirements

- Two library controller (HBC) cards

- Two drive controller (HBT) cards

- Minimum SL3000 firmware version FRS_3.0 and SLConsole version 5.00

- Hardware activation file (see "Hardware Activation Files")

- HLI host with TCP/IP or FC-SCSI host using ACSLS (RE is not available to hosts using a native FC-SCSI interface)

## Redundant Electronics Overview

If the library controller or drive controller experiences errors, operations can switch to the standby controller with minimal disruption to the library and host operations. The library controller and drive controller installed on the same side of the card cage are always switched as a pair. Failover can be initiated automatically or manually. A failover cannot occur if:

- The standby library or drive controller is in a fault or eject state

- The standby code is not running on the standby library or drive controller cards

- A firmware download or card initialization is in progress

In a failover, the active library controller attempts to complete all in-process jobs and copies the cartridge database to the standby controller card. If the database cannot be copied (usually only in a sudden failure), you must perform and audit after the failover completes (see "Audits"). Any in transit cartridges are returned to their home slots. If a cartridge cannot be moved to its home slot, it is moved to a library system cell. The host must return the cartridge to its home cell (see library management software documentation).

After all in-process jobs have completed or timed out, the card roles switch. Active software is brought up on the standby controller. This controller becomes active and the previously active controller becomes the standby. If the standby software cannot be brought up on the previously active controller, the controller enters a fault state.

### Automatic Failover

An automatic failover can be initiated by either the active or standby library controller.

The active library controller initiates an automatic failover when:

- Its partner drive controller card is not installed or it is not communicating.

- It detects a catastrophic internal software error.

The standby library controller initiates an automatic failover if the active controller is not functioning normally.

### Manual Failover

Before initiating a manual switch, you should verify that the standby library and drive controllers are running normally. You can initiate a manual switch using:

- Host tape management (ACSLS or ELS): Failover can be initiated from either the active or standby library controller. The standby library controller accepts only `set host path group` and `force switchover` HLI requests.

- SLConsole: Failover is initiated from the active library controller only (see "Manual Redundant Electronics Switch").

- CLI: Failover can be initiated from either the active or standby library controller. This function is available to your Oracle support representative only.

You may want to perform a manual switch after initial installation of the standby cards, after a firmware upgrade, or periodically to check the failover function is working properly. It is not possible to manually switch the library controllers without the drive controllers — the controllers are always switched as a pair.

### Connections

Each library controller card requires a unique IP address. For libraries with Dual TCP/IP, each card requires two unique IP addresses: one for the primary port (2B) and one for the secondary (2A) port. A library equipped with both RE and Dual TCP/IP requires four unique IP addresses.

The failover process is minimally disruptive to host operations.

- Users of tape management software (Symantec or Virtual Storage Manager) do not see an interruption.

- HLI host applications (ACSLS and ELS) queue requests during the failover process for completion after the failover switch. For ACSLS, only mount and dismount requests are affected (see the ACSLS and ELS documentation).

- SLConsole and CLI connections are terminated. You must re-establish connections to the library using the IP address or DNS alias of the new active library controller (the former standby controller).

### Firmware Upgrades

Firmware upgrades for libraries with RE are minimally disruptive to library operations. New code is loaded and unpacked simultaneously on the active and standby controller cards and on all devices. The code is then activated, and the active and standby controllers and most devices are re-initialized. Under most circumstances, robot initialization is bypassed.

The loading, unpacking, and activation of code are not disruptive to library operations until the library is rebooted. During the reboot process (which takes approximately 10 minutes), the HLI host applications (ACSLS and ELS) queue all mount and dismount requests. After the reboot is complete, the queued requests are submitted to the library controller.

See "Upgrade Library Firmware" for firmware download and activation information.

## Controller Card Status

Controller card status is indicated by LEDs on the card and displayed in SLConsole.

### LEDs

The LEDs and meanings are the same on both card types (HBC and HBT).

Table 7-1 LED Status Indicators

LED | Definition
--- | ---
ACTIVE - Green | Card is functioning as the active and is running active code.
STANDBY - Amber | Card is functioning as the standby and is running standby code.
FAULT - Red | Card has experienced a serious error.
EJECT OK - Blue | Support representative can safely initiate a card eject.

### SLConsole Status

Some SLConsole screens identify the individual library controller with an A or B suffix. "A" indicates the bottom card slot and "B" indicates the top card slot. To display the status the controller cards in SLConsole, see "Display Redundant Electronics Information".

Table 7-2 SLConsole Controller Card Statuses

Status | Definition
--- | ---
Duplex: Software ready, switch possible | Active library controller is functioning normally.
Not installed | Card is not installed in the library.
Ok | Active or standby drive controller card is functioning normally.
Pre-standby: Software not ready | Standby library controller card is loading standby code and is not ready to be used in an automatic failover or manual switch.
Standby: Software ready | Standby library controller card is functioning normally and can be used for an automatic failover or manual switch.

## Display Redundant Electronics Information

1. Select Tools > System Detail.

2. Click the Redundant Electronics folder to display summary information.

3. For detailed information about each card, expand the Redundant Electronics folder in the navigation tree.

4. Select a card (see "SLConsole Status" for status meanings):

   1. hbca: Library controller, A (bottom) slot

   2. hbcb: Library controller, B (top) slot

   3. hbta: Drive controller, A (bottom) slot

   4. hbtb: Drive controller, B (top) slot

## Manual Redundant Electronics Switch

This procedure is not available at the local operator panel.

1. Verify the device state of the card indicates "switch is possible" (see "Display Redundant Electronics Information").

2. Select Tools > Diagnostics.

3. Select the Redundant Electronics folder

4. Click Apply to begin the switch process. If there is a problem with the standby library and drive controller cards, you are not allowed to continue with the switch.

5. If there are no errors, click Yes.

6. Click OK to log off the SLConsole.

7. Wait until the switch is complete before logging back into the library. You must specify the IP address or DNS alias of the new active controller to log in.