## 8.1 SAP HANA System Replication Details
Detailed information from the M\_SERVICE\_REPLICATION and the M\_SYSTEM\_REPLICATION monitoring views about system replication.
General Overview
| Column              | Description                                              |
|---------------------|----------------------------------------------------------|
| Site ID 1           | Generated ID of the primary site                         |
| Secondary Site ID 2 | Generated ID of the secondary site                       |
| Service             | Nameof the service                                       |
| Volume ID           | Persistence volume ID                                    |
| Operation Mode      | ● LOGREPLAY ● LOGREPLAY_READACCESS ● DELTA DATA SHIPPING |
| Column              | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|---------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Replication Mode    | Configured replication mode: ● SYNC: synchronous replication with acknowledgement when buffer has been written to disk on the secondary system ● SYNCMEM: synchronous replication with acknowledge­ ment when buffer arrived in memory on the secondary system ● ASYNC: asynchronous replication where the primary does not wait for the acknowledgement ● UNKNOWN:is set if replication mode could not be deter­ mined (this might be the case, for example. if there are communication errors when getting status information from a service).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Replication Status  | Current status of replication: ● UNKNOWN:secondary did not connect to primary since last restart of the primary ● INITIALIZING: initial data transfer is running, in this state, the secondary is first usable when this is finished ● SYNCING: secondary is syncing again (for example, after a temporary connection loss or restart of the secondary) ● ACTIVE: initialization or sync with primary is complete and secondary is continuously replicating. If crash oc­ curs, no data loss will occur in SYNC replication mode. ● ERROR: replication cannot take place because the sec­ ondary system is not accessible (details can be found in                                                                                                                                                                                                                                                                                                                                                                                 |
| Replication Details | Additional information for Replication Status, for example, the error text if status is ERROR.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Full Sync           | Indicates if the service is currently operating in sync replica­ tion mode with the full sync option set. If full sync is enabled in a running system, full sync might not be active immediately. This is done to prevent the system from blocking transactions immediately when setting the pa­ rameter to true. Instead, in a first step, full sync has to be en­ abled. In a second step it is internally activated, when the secondary is connected and becomes ACTIVE. ● DISABLED: full sync is not configured at all ● ENABLED: full sync is configured, but it is not yet active, so transactions do not block in this state. To become ac­ tive the secondary has to connect and Replication Sta­ tus has to be ACTIVE. ● ACTIVE: full sync mode is configured and active. If a con­ nection of a connected secondary is getting closed, transactions on the primary side will block in this state. If full sync is enabled when an active secondary is currently connected, the FULL_SYNC will be immediately set to AC­ TIVE. |
## Column
## Description
| Secondary Fully Recoverable            | TRUE: No full data backup is needed after takeover on secon­                                                                                                                                                                                                                                                                                                             |
|----------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Secondary Active                       | Status of the secondary node (also see ACTIVE_STATUS in M_SERVICES)                                                                                                                                                                                                                                                                                                     |
| Secondary Connect Time                 | Timestamp the secondary connected to the primary. If there are reconnects from the secondary side, this field contains the last connect time.                                                                                                                                                                                                                           |
| Secondary Reconnect Count              | Number of reconnects from secondary side for this service.                                                                                                                                                                                                                                                                                                              |
| Secondary Failover Count               | Number of failovers for this service on secondary side.                                                                                                                                                                                                                                                                                                                 |
| Buffer Full count                      | Number of times, the asynchronous replication buffer was full since last service restart (only relevant for replication mode async; 0 for replication modes sync/syncmem).                                                                                                                                                                                              |
| Log Positions                          |                                                                                                                                                                                                                                                                                                                                                                         |
| Column                                 | Description                                                                                                                                                                                                                                                                                                                                                             |
| Last Log Position                      | Last known log position on primary                                                                                                                                                                                                                                                                                                                                      |
| Last Log Position Time                 | Timestamp of last known log position                                                                                                                                                                                                                                                                                                                                    |
| Replayed Log Position                  | Log end position of the last known replayed log buffer on secondary site                                                                                                                                                                                                                                                                                                |
| Replayed Log Position Time             | Timestamp of the last known replayed log buffer on the sec­ ondary site                                                                                                                                                                                                                                                                                                  |
| Last Shipped Log Position Time         | Timestamp of last log position being shipped to secondary                                                                                                                                                                                                                                                                                                               |
| Shipped Log Buffer Count               | Number of log buffers shipped to secondary                                                                                                                                                                                                                                                                                                                              |
| Shipped Log Buffers Total Size (Bytes) | Size of all log buffers shipped to secondary                                                                                                                                                                                                                                                                                                                            |
| Shipped Log Buffers Total Time (µs)    | Time taken to ship all the log buffers to the secondary. ● SYNC/SYNCMEM: total round trip time to send the log buffers and receive the acknowledgment. ● ASYNC: start time when sending the log buffers, end time when the OSreports that the log buffers were sent (and the log shipping buffer space was freed). This could be shorter than the SYNC/SYNCMEM duration |
| Time delay (ms)                        | Time delay between the last shipped log position time and the replayed log position time on the secondary                                                                                                                                                                                                                                                               |
| Size delay (Bytes)                     | Size delay between the last shipped log position size and the replayed log position size on the secondary (1 log position = 64 bytes)                                                                                                                                                                                                                                   |
## Savepoints
| Column                              | Description                                 |
|-------------------------------------|---------------------------------------------|
| Last Savepoint Version              | Last savepoint version on primary           |
| Last Savepoint Log Position         | Log position of current savepoint           |
| Last Savepoint Start Time           | Timestamp of current savepoint              |
| Last Shipped Savepoint Version      | Last savepoint version shipped to secondary |
| Last Shipped Savepoint Log Position | Log position of last shipped savepoint      |
| Last Shipped Savepoint Time         | Timestamp of last shipped savepoint         |
## Full Data Replica
| Column                                       | Description                                              |
|----------------------------------------------|----------------------------------------------------------|
| Full Data Replica Shipped Count              | Number of full data replicas shipped to secondary        |
| Full Data Replica Shipped Total Size (Bytes) | Total size of all full data replica shipped to secondary |
| Full Data Replica Shipping Total Time (µs)   | Duration for shipping all full data replica              |
| Last Full Data Replica Shipped Size (Bytes)  | Size of last full data replica shipped to secondary      |
| Start Time of Last Full Data Replica         | Start time of last full data replica                     |
| End Time of Last Full Data Replica           | End time of last full data replica                       |
## Delta Data Replica
This information is only displayed if the operation mode is delta\_datashipping .
| Column                                        | Description                                                |
|-----------------------------------------------|------------------------------------------------------------|
| Delta Data Replica Shipped Count              | Number of delta data replicas shipped to secondary         |
| Delta Data Replica Shipped Total Size (Bytes) | Total size of all delta data replicas shipped to secondary |
| Delta Data Replica Shipped Total Time (µs)    | Duration for shipping of all delta data replicas           |
| Size of Last Delta Data Replica (Bytes)       | Size of last delta data replica                            |
| Start Time of Last Delta Data Replica         | Start time of last data delta replica                      |
| End Time of Last Delta Data Replica           | End time of last data delta replica                        |
## Log Shipping Backlog
| Column                                   | Description                                                                                                                                                                                                                                                                                                                                                                                                     |
|------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Current Replication Backlog Size (Bytes) | Current replication backlog in bytes, this means, size of all log buffers that have been created on primary site, but not yet sent to the secondary site. Even in replication modes sync/syncmem this column can have a value different from 0. Here it represents the size of log buffers that are in the local send queue (max number of those buffers is the number configured log buffers on primary site). |
| Max Replication Backlog Size (Bytes)     | Max replication backlog in bytes (max value of BACK­ LOG_SIZE since system start).                                                                                                                                                                                                                                                                                                                               |
## Column
Current Replication Backlog Time (µs)
Max Replication Backlog Time (µs)
## Log Replay
This information is only displayed if the operation mode is logreplay and logreplay\_readaccess .
| Column                          | Description                                                                                                                              |
|---------------------------------|------------------------------------------------------------------------------------------------------------------------------------------|
| Replay Backlog Size (Bytes)     | Specifies the size of all log buffers that have been shipped to the secondary site but have not yet been replayed on the secondary site. |
| Max Replay Backlog Size (Bytes) | Specifies the maximum value of the REPLAY_BACK­ LOG_SIZE since the system startup.                                                        |
| Replay Backlog Time (µs)        | Specifies the time difference between the time of the last shipped log buffer and the last replayed log buffer on the secondary site.    |
| Max Replay Backlog Time (µs)    | Specifies the maximum value of REPLAY_BACKLOG_TIME since the system startup.                                                             |
## Related Information
SQL and System View Reference [page 269]