Technical data

Configuring and Managing FTP
15.2 Solving FTP Problems
• Increase the inactivity timer
These logical names are described in the following sections.
15.2.1.1 Buffer Sizes
Changing the window size of the send and receive buffers can improve network
performance. To set or modify the window size, define or redefine the logical
name TCPIP$FTP_WNDSIZ.
• For a systemwide change, redefine this logical name in the system table.
Edit the SYS$MANAGER:TCPIP$SERVICES_SETUP file to add this line:
$ DEFINE /SYSTEM /EXEC TCPIP$FTP_WNDSIZ 4096
• For the change to apply to one user, define the logical name in the
LOGIN.COM file in the default directory of that user.
For noisy lines, such as modems, you should set the value of the TCPIP$FTP_
WNDSIZ parameter to a lower number.
15.2.1.2 File Allocation and Extension Sizes
FTP logical names preallocate disk blocks. FTP tells RMS to truncate unused
blocks so that disk space is not wasted. This can affect RMS performance.
To reduce the RMS overhead, use the following logical names:
• TCPIP$FTP_FILE_ALQ — Modifies the allocation quantity.
Specifies the number of blocks to be allocated to a disk file when it is created.
For example:
$ DEFINE /SYSTEM/EXEC TCPIP$FTP_FILE_ALQ 50000
• TCPIP$FTP_FILE_DEQ — Default extension quantity.
Specifies the number of blocks to be added when RMS automatically extends
the file. For example,
$ DEFINE TCPIP$FTP_FILE_DEQ 100
Define these logicals in the TCPIP$SYSTARTUP.COM procedure, or in the
SYS$MANAGER:STARTUP_VMS.COM file before the command that starts
TCP/IP Services. Because disk quotas may control the system, these logical
names are defined by default as zero (system RMS defaults) or are undefined. For
file transfers between hosts that both use VMS Plus mode, these logical names
have no effect.
15.2.1.3 Inactivity Timer
The larger the inactivity timer value, the longer FTP maintains sessions without
timing out. Excessive inactive sessions might slow down performance, degrade
security, or prevent other users from establishing sessions.
To increase the inactivity timer, change the value of the
TCPIP$FTPD_IDLETIMEOUT logical name. The default is 15 minutes. For
example:
$ DEFINE TCPIP$FTPD_IDLETIMEOUT 01:00:00
Configuring and Managing FTP 15–7