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Adjusting the Number of Retries for DB Redundancy Connection via TB_CONN_MAX_RETRIES Environment Variable

Document Type | Troubleshooting

Category | Monitoring/Inspection

Applicable Product Versions | 6FS07, 6FS07PS, 7FS02, 7FS02PS

Error Code | 2131

Document Number | TMOTS015

 

Issue

When connecting to the DB through a redundant alias in the tbdsn.tbr file, retries are performed upon connection failure.
When attempting to connect to a terminated DB, it takes more than one minute to receive a failure response (TBR-2131: Generic I/O error).
 
 

Cause

When connecting to the DB via the redundant alias set in the tbdsn.tbr file, 20 reconnection attempts are internally made as the default count.
During this process, depending on network settings, the โ€˜FAILโ€™ response from the DB can be delayed by more than one minute, causing overall response delays.
TEST=(
 (INSTANCE=(HOST=192.168.47.2)
 (PORT=8629)
 (DB_NAME=tibero)
 )
 (INSTANCE=(HOST=192.168.47.3)
 (PORT=8629)
 (DB_NAME=tibero)
 )
)
 
 

Solutions

Apply the patch to resolve the issue. (Applied patch: 328257a)
With patch 328257a, the environment variable TB_CONN_MAX_RETRIES was added to control the number of reconnection attempts from the client to the DB during failover.
Note
Apply the patch through technical support provided by Tmax Tibero.
 
By setting the TB_CONN_MAX_RETRIES environment variable, you can flexibly adjust the number of retries, reducing unnecessary wait times.

When TB_CONN_MAX_RETRIES environment variable is not set

$ tbsql sys/tibero

$ cat tbcli_20240909153346_14880.log | grep "clnt_comm_connect" | wc -l

โ†’ Outputs 21

After 1 failed connection attempt, 20 retries are executed.
02-23 15:33:46.659800 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
02-23 15:33:46.660223 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
02-23 15:33:46.660880 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
...
02-23 15:33:46.665283 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
02-23 15:33:46.665625 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
02-23 15:33:46.665709 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
02-23 15:33:46.666092 [14880][DBG] clnt_comm_:048   clnt_comm_connect:comm[0x1277110] dsn_info[0x127cb74] err_info[0x127dea8]
 

When TB_CONN_MAX_RETRIES=5 environment variable is set

$ tbsql sys/tibero

$ cat tbcli_20240909153523_15394.log | grep "clnt_comm_connect" | wc -l
โ†’ Outputs 6
After 1 failed connection attempt, 5 retries are executed.

 
 

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