SubSection
TcpNoDelay = <value>
Values: 0, 1
E.g. TcpNoDelay = 1
Optional parameter Indicates whether the TCP Delay option should be disabled (0) or enabled (any other value)
SendSpace & RecvSpace Controls the size of the receive and send buffers for TCP/IP sockets. Internally, HPSS servers and clients attempt to set these buffers sizes explicitly, but other utilities may not. Typically, the RecvSpace and the SendSpace are equal; however, this is not mandated.
Setting either of these values in excess of the system maximum will result in a value <= the system maximum. The maximum can be observed/changed on AIX using the “no” command and observing/setting the sb_max parameter. There is no portable mechanism for determining the system maximum. Consequently, the specified values may be reduced until an acceptable value is obtained. This process involves a
RFC1323 Controls whether large TCP window sizes are used. Usually turned on (1) for higher throughput networks (e.g. SP/x switch, Gigabit Ethernet, etc.) and turned off (0) for lower throughput networks (e.g. 10/100 Mb ethernet, FDDI, etc.) Large windows provide for increased performance over some networks, but may have a negative performance impact on others. NOTE: currently the ability to enable or disable RFC 1323 support in this manner is specific to AIX. (An equivalent setting for Solaris is the tcp_wscale_always flag, set with the command “ndd /dev/tcp tcp_wscale_always”.)
The WriteSize allows the size of the individual write requests to the TCP/IP connections to be configured. The default behavior (if no entry in the file matches a connection or if zero is entered for the value of this field) is that the size of the write request is the size of the data buffer. On some networks (e.g. the SP/x switch), improved performance has been measured by using a smaller value (e.g. 32KB) for the size of the individual writes to the network. If no entry is found that matches a network connection or the value specified is zero, HPSS will query an environment variable, HPSS_TCP_WRITESIZE, and use that value, if set and
The TcpNoDelay option determines whether HPSS will enable or disable the algorithm that tries to improve performance from small network writes. This algorithm attempts to coalesce small writes to a TCP/IP connection so they can be sent in a single packet by delaying physical writes to the network. HPSS typically disables this algorithm so that delays are not experienced while sending Mover Protocol and parallel data transfer headers. However, if this causes a performance degradation on a specific network (e.g., causes smaller than optimal packet sizes for large transfers), this can be disabled for data transfer connections.
Network Options Stanza Specific Rules:
•The first matching entry found in the file will be used to determine the network options used for that connection.
•Multiple “Source Interface Name” SubStanzas may be included within the “Network Options” Stanza. A “Default” Source Interface Name SubStanza may be specified.
•The Source Interface Name SubStanza may specify one or more names [ subject to the HPSS.conf line character limit (including the “= {“.) ] NOTE: Do not include the quotes when specifying Default.
•Destination IP Address must be specified in Decimal Dot Notation.
HPSS Installation Guide | July 2008 |
Release 6.2 (Revision 2.0) | 271 |
