STATUS CODE 24: The error "socket write failed" appear during backups performed with Veritas NetBackup (tm).

Article:TECH34183  |  Created: 2004-01-02  |  Updated: 2013-10-23  |  Article URL http://www.symantec.com/docs/TECH34183
Article Type
Technical Solution

Product(s)

Environment

Issue



STATUS CODE 24: The error "socket write failed" appear during backups performed with Veritas NetBackup (tm).

Error



EXIT STATUS 24: socket write failed

Solution



Overview:
The transmission control protocol (TCP) network parameter tcp_ip_abort_interval may cause this error if it has been tuned incorrectly.

The tcp_ip_abort_interval is the total retransmission timeout value for a TCP connection in milliseconds. For a given TCP connection, if TCP has been retransmitting for tcp_ip_abort_interval period of time and it has not received any acknowledgment from the other endpoint during this period, TCP closes this connection. By default, the tcp_ip_abort_interval parameter is 480000 milliseconds (8 minutes).

Troubleshooting:
To obtain the current tcp_ip_abort_interval parameter value, the following command can be run.  This is an operating system command and will be found in one of the system directories, depending on the platform.  For example, /usr/sbin/ndd can be found on Solaris systems.

# ndd -get /dev/tcp tcp_ip_abort_interval

When tuning the tcp_ip_abort_interval, the following TCP network parameter values must also be taken into consideration:
tcp_rexmit_interval_initial: The initial retransmission timeout (RTO) value for a TCP connection in milliseconds. The default value is 3000 milliseconds (3 seconds).
tcp_rexmit_interval_min: The minimum retransmission timeout (RTO) value in milliseconds. The default value is 400 milliseconds.
tcp_rexmit_interval_max: The maximum retransmission timeout value (RTO) in milliseconds. The default value is 60000 milliseconds (60 seconds).
To obtain the above current TCP parameter values, the following commands can be run:
# ndd -get /dev/tcp tcp_rexmit_interval_initial
# ndd -get /dev/tcp tcp_rexmit_interval_min
# ndd -get /dev/tcp tcp_rexmit_interval_max

Log Files:  N/A

Resolution:
If the tcp_ip_abort_interval timer value is reduced to a value less than the tcp_rexmit_interval_max timer value or any other tcp_rexmit variable (shown above) then connections can get aborted. This is due to the tcp_ip_abort_interval timer expiring before the tcp_rexmit_interval_max (or other tcp_rexmit variable) timer is reached. When the tcp_ip_abort_interval timer value is reached, the TCP connection is closed (RESET signal).

The TCP connection reset will be presented in the bpbkar log file as a "Errno = 32: Broken pipe" error message. This error message will then be followed with an "Exit status = 24: socket write failed" error message.

If the tcp_ip_abort_interval parameter value must be reduced, the value should be at least four times greater than the tcp_rexmit_interval_max parameter value as recommended by Sun Microsystems. In addition, Sun Microsystems recommends the tcp_rexmit_interval_max value to be at least eight times the value of  tcp_rexmit_interval_min.
It is important to note that the inetd process needs to be restarted after modifying these parameters. If this does not occur, the current tcp_rexmit parameter values will be retained.
The Sun Microsystems default TCP parameter values are adequate for the majority of servers and applications currently in use.
The default TCP parameter values should not be modified without adequate research and should follow Sun Microsystems recommendations.

Supplemental Materials

SourceError Code
Value24
DescriptionNetBackup Error 24: socket write failed

Legacy ID



271200


Article URL http://www.symantec.com/docs/TECH34183


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