SAP HANA Network FAQ
1. What is the meaning of network in the context of this SAP mean?
"Network" in the context of this SAP means all communications between different processes regardless of their distance and the kind of physical connection.
2. Which indications exist for SAP HANA network problems?
SQL: "HANA_Configuration_MiniChecks" (SAP s 1969700) returns a potentially critical issue (C = 'X') for one of the following individual checks:
| Check ID | Details |
| 1510 | Avg. intra node send throughput (MB/s) |
| 1512 | Avg. inter node send throughput (MB/s) |
| 1520 | Retransmitted TCP segments (%) |
| 1522 | Bad TCP segments (%) |
See SAP 1999993 for more information related to SAP HANA Mini Checks.
A high amount of database threads are active with status 'Network Read' or 'Network Write' (see SAP 2114710).
3. What types of networks exist in SAP HANA environments?
The following main communication scenarios exist in SAP HANA environments:
| SAP HANA Scenario | Details | Example |
| server intra-node | Communication of a SAP HANA server process with another SAP HANA server process on the same host | Topology request: indexserver <-> nameserver |
| server inter-node | Communication of a SAP HANA server process with another SAP HANA server process on a different host | Access to distributed table partitions: indexserver <-> indexserver |
| client / server | Communication of a SAP HANA server process with a client process (SAP 2200772) | ABAP workprocess request: indexserver (SQL executor thread) <-> SAP workprocess |
| system replication | Communication between SAP HANA system replication sites (SAP 1999880) | Synchronous log shipping from primary to secondary system |
4. What are typical problems in the network area?
The following general areas are typically critical with respect to the network:
| Area | Details |
| Latency | The latency or round trip time indicates how long it takes to send a request across the network. Latency is often an important performance factor in SAP HANA environments taking into account the efficient server processing due to column store and in memory. |
| Bandwidth | The bandwidth defines the amount of data that can be transferred across network. if the bandwidth limit is reached, performance can drop dramatically. |
| Terminations | Network related terminations can critically impact the availability and stability of SAP HANA. |
5. How can I perform general network troubleshooting in SAP HANA environments?
See SAP 2081065 for troubleshooting general network problems in SAP HANA environments.
See SAP 1100926 for general remarks regarding network performance.
6. Are there specific network requirements for SAP HANA area?
The following documents describe network requirements for certain SAP HANA areas:
- SAP HANA TDI - Network Requirements
- Network Recommendations for SAP HANA System Replication
7. What are important network related SAP HANA parameters?
The following table lists important SAP HANA parameters related to the network:
| Parameter | Unit | Network Area | SAP | Details |
global.ini -> [communication] -> internal_network | | server | 2242514 | Defines the internal network used for SAP HANA server process communication. |
global.ini -> [communication] -> listeninterface | | server | 2183363 | Controls how the SAP HANA server processes communicate with each other. |
global.ini -> [internal_hostname_resolution] -> ... | | server | 2183363 | Defines the SAP HANA internal host name resolution |
global.ini -> [public_hostname_resolution] -> ... | | server | 2036111 | Defines the SAP HANA public hostname resolution |
global.ini -> [system_replication_hostname_resolution] -> ... | | system replication | 2183363 | Defines the SAP HANA system replication host name resolution |
global.ini -> [system_replication] -> enable_data_compression | | system replication | 1999880 | (De-)activates compression of data being sent to secondary site |
global.ini -> [system_replication] -> enable_log_compression | | system replication | 1999880 | (De-)activates compression of log being sent to secondary site |
indexserver.ini -> [distribution] -> client_distribution_mode | | client / server | 2200772 | Controls to which SAP HANA scale-out node a specific client request connects |
indexserver.ini -> [session] -> socket_keepalive | | client / server | 1836774 | Controls dead connection detection |
indexserver.ini -> [session] -> tcp_keepalive_time | s | client / server | 1836774 | Time between the last packet sent and the first dead connection detection probe |
indexserver.ini -> [session] -> tcp_keepalive_intvl | s | client / server | 1836774 | Time between subsequent dead connection detection probes |
indexserver.ini -> [session] -> tcp_keepalive_probes | | client / server | 1836774 | Number of unacknowledged probes before reporting a dead connection |
indexserver.ini -> [sql_client_network_io] -> buffer_size | rows | client / server | 2119087 | Defines the buffer size for the client network trace |
indexserver.ini -> [sql_client_network_io] -> enabled | | client / server | 2119087 | Controls the client network trace |
8. What are SAP HANA errors related to network and communication?
The following table discusses common SAP HANA errors related to network communications. Be aware that sometimes the "2nd Level Error" messages cover quite similar aspects. If the recommendations for a specific "2nd Level Error" don't apply, you can therefore check for recommendations provided for similar errors related to the same main error.
| Error | 1st Level Error | 2nd Level Error | Details | ||||||||||||||||||||||||
| -709 | Cannot connect to VolumeID= | Cannot connect to host : [Unknown host] | This error indicates that SAP HANA can't connect to a disk volume assigned to the specified SAP HANA host, because the host is not known. Check the network configuration and the availability of the host and the disk area in order to resolve this issue. | ||||||||||||||||||||||||
| -813 | Cannot connect to VolumeID= | Cannot connect to host : [Connection refused] | This error indicates that SAP HANA can't connect to a disk volume assigned to the specified SAP HANA host, because the connection isn't accepted. Check the network configuration and the availability of the host and the disk area in order to resolve this issue. | ||||||||||||||||||||||||
| -813 | Cannot connect to VolumeID= | Cannot connect to host : [Connection timed out] | This error indicates that SAP HANA can't connect to a disk volume assigned to the specified SAP HANA host, because the connection to the host times out. Check the network configuration and the availability of the host and the disk area in order to resolve this issue. | ||||||||||||||||||||||||
| -10108 | Session has been reconnected | This error indicates that a connection / session to the SAP HANA server has been reconnected. Normally this should happen transparently without terminating the client transaction. Reasons for terminations are:
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| -10709 | Connection failed | connect timeout expired | This error indicates that the defined connection timeout was reached. Typical reasons are:
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| -10709 | Connection failed | no reachable host left | This error indicates that none of the SAP HANA server nodes configured on client side can be reached. Typical reasons are:
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| -10709 | Connection failed | RTE:[89001] Cannot resolve host name '' rc=-3: Temporary failure in name resolution | This error indicates a problem in the host name resolution. Typical reasons are:
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| -10709 | Connection failed | RTE:[89006] System call 'send' failed, rc=32:Broken pipe | This error indicates that the network pipe was terminated. Typical reasons are:
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| -10709 | Connection failed | RTE:[89006] System call 'connect' failed, rc=111:Connection refused | This error indicates that a connection to the SAP HANA server is refused by the server or another component. Typical reasons are:
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| -10709 | Connection failed | RTE:[89006] System call 'connect' failed, rc=113:No route to host | This error indicates that the network stack isn't able to set up a route to the target host. Typical reasons are:
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| -10709 | Connection failed | RTE:[89006] System call 'connect' failed, rc=10060:A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond | This error indicates that a connection request didn't receive a response from the target host. Please check:
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| -10709 | Connection failed | RTE:[89006] System call 'connect' failed, rc=10061:No connection could be made because the target machine actively refused it | This error indicates that a connection is refused by the target host. Typical reasons are:
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| -10709 | Connection failed | RTE:[89006] System call 'recv' failed, rc=104:Connection reset by peer | This error indicates that the remote host has dropped the network connection. Typical reasons are:
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| -10709 | Connection failed | RTE:[200107] Missing logon credential | This error indicates that no appropriate logon credentials were provided. Typical reasons are:
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| -10807 | System call 'recv' failed | rc=104:Connection reset by peer | This error indicates that the target host can't be reached. Typical reasons are:
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| -10821 | Session not connected | This error indicates that a connection to SAP HANA doesn't exist, e.g. because it was never established successfully or because it terminated due to another error. In ABAP environments this error activates the reconnect mode (SAP 98051). |
9. Which error codes activate the SAP ABAP reconnect mode?
The SAP ABAP reconnect mode is entered in order to avoid massive terminations and dumps in case of general database access issues (SAP 98051). The following error codes activate the reconnect mode:
-10708, -10709, -10715, 10807, -10821
10. Why the threads waiting long for the network?
Most usual call stacks of threads waiting for network requests are:
__read_nocancel
recv ()
If the threads appear to be stuck waiting for the network, Below is the following causes of this issue
| SAP | Re-examination | Details |
| 2338828 | <= 112.03 | If the connection is having M_CONNECTIONS.CONNECTION_STATUS = 'RECEIVING' and the call stack for the related thread contains Crypto::SSL::Filter::receive then the problem described in SAP 2338828 must be responsible: A runtime dump can cause network data packet loss when SSL is used. |