HP TCP/IP Services for OpenVMS

Previous Contents Index

22.10.7 Restoring a Container File System

For a typical image restore, follow normal OpenVMS procedures.

For a nonimage restore, an additional step is required after the restore. The Files--11 file identifiers are recorded in the container file. These must be updated by the TCP/IP management command ANALYZE CONTAINER /REPAIR.

This extra step is also required for an image restore if the save set is being restored with the /NOINITIALIZE qualifier to a volume with a different label or if it is being restored to a bound volume set that has a member that was added since the time of the image backup.

22.11 Setting Up NFS Security Controls

The NFS server and the OpenVMS operating system provide many levels of security controls you can use to protect your file systems. Section 22.1.3, Section 22.1.4, and Section 22.1.7 describe how the server uses the proxy and export databases to restrict client access, and how to use OpenVMS account privileges and file protections to control access to files and directories.

The NFS server provides additional security controls through the use of the noproxy_enabled attribute. You can set this attribute in the NFS server site-specific startup file SYS$STARTUP:TCPIP$NFS_SERVER_SYSTARTUP.COM.

The server uses this attribute while it is running. If the attribute is set, a proxy is not required for users attempting to access the NFS server. For more information about the NFS server attributes, see Table 22-3.

22.12 Modifying NFS Server Attributes

You can modify the way the NFS server works by specifying NFS server attributes in the SYSCONFIGTAB database. The characteristics of the NFS server that you can modify include:

To make permanent modifications, use the SYSCONFIGDB utility to include the new settings in the SYSCONFIGTAB.DAT file, as described in the HP TCP/IP Services for OpenVMS Tuning and Troubleshooting guide.

To make the changes take effect, shut down and then restart the NFS server. For example:


Future upgrades or installations will not overwrite the definitions in the SYSCONFIGTAB file.

Modifying NFS server characteristics can affect NFS server performance. Be sure you understand the impact (review Section 22.15) before making any changes.

Table 22-3 describes the NFS server attributes that you can modify to affect NFS server performance.

Table 22-3 Modifying NFS Server Attributes
Attribute Description
noproxy_enabled Enables the use of the noproxy_uid and noproxy_gid attributes. If this attribute is not set to 1, proxies are required for server access.

If the value is 0, files owned by a user that is not in the proxy database are assumed to be owned by UID=-2/GID=-2. If the value is 1, files owned by a user not in the proxy database are reported to be owned by the values of the noproxy_uid and noproxy_gid attributes.

noproxy_uid Specifies the default UID when a user cannot be translated by the proxy.
noproxy_gid Specifies the default GID when a user cannot be translated by the proxy.
tcp_threads Specifies the number of concurrent TCP threads within the server. A value of zero will disable the TCP protocol.
udp_threads Specifies the number of concurrent UDP threads within the server. This value must not be zero.
vnode_age Specifies the number of seconds in the time interval since the last file access request.

The server keeps an activity timestamp for each opened file to help manage the open file cache. You can also modify this value with the /INACTIVITY qualifier to the SET NFS_SERVER command.

The default setting for this variable is 120, or 2 minutes. Be careful not to set this value to a small interval; this might reduce performance.

ovms_xqp_plus_enabled Controls the way the NFS server accesses the directory cache. For more information, see Section 22.15.3.

22.13 Modifying File System Characteristics

The file SYS$STARTUP:TCPIP$NFS_STARTUP.COM contains definitions of logical names that set the file system parameters. To change the settings of these logical names, define them in the SYS$STARTUP:TCPIP$SYSTARTUP.COM command procedure by using the /EXECUTIVE_MODE and /SYSTEM qualifiers.

Table 22-4 describes these logical names.

Table 22-4 File System Logical Names
Logical Name Description
TCPIP$CFS_CACHE_LOW_LIMIT Defines the minimum size of the free buffer list. When the list is smaller than the value of this logical name, the file system starts to reclaim used buffers.

The default is 4 buffers.

The free buffer list needs at least 4 free buffers (not taken by cache). If the actual number of free buffers is less than TCPIP$CFS_CACHE_LOW_LIMIT, the used buffers are returned to the free list until the size of the free list reaches the value of TCPIP$CFS_CACHE_HIGH_LIMIT.

TCPIP$CFS_CACHE_HIGH_LIMIT Defines the number of buffers the file system tries to keep in the free buffer list.

The default is 8 buffers. See TCPIP$CFS_CACHE_LOW_LIMIT.

In a busy server environment, setting this parameter higher is likely to improve performance.

TCPIP$CFS_CACHE_SIZE Defines the maximum number of cache buffers to be allocated.
TCPIP$CFS_NAME_CACHE_SIZE Establishes the size of the file name cache. For more information, see Section 22.15.3.
TCPIP$CFS_ODS_CACHE_SIZE Establishes the size of the ODS cache. For more information, see Section 22.15.3.
TCPIP$CFS_PREFER_VERSION Controls whether the number after a dot in a file name is interpreted as a file extension or a version number. By default, a dot followed by a number is assumed to be a file extension. When this logical name is set, the number is assumed to be a version number.

This logical name applies to ODS-5 volumes using typeless directories.

TCPIP$CFS_TRANSFERSIZE Defines the optimum size (in bytes) of the data transferred between server and client on READ and WRITE operations.

The default is 8K bytes (8192 bytes). This value is used in most NFS server implementations.

TCPIP$CFS_SHOW_VERSION Sets the SHOW_VERSION logical name ON or OFF. If ON, the NFS server returns to the client file names with version numbers, even if there is only one version of the file.

The default is OFF.

TCPIP$CFS_MODUS_OPERANDI Defines various operating modes. Use only under the advice of your HP support representative.
TCPIP$CFS_FATAL_MESSAGES Defines the terminal device to which the important error messages are directed, in addition to the normal error messages that are sent to the operator's console.

The default is _OPA0:.

22.14 File Locking

TCP/IP Services supports a partial implementation of NFS network locking, which allows users to lock files. The software coordinates locks among remote users and between remote and local users. The file locking features is applicable regardless of whether the OpenVMS Record Management Services (RMS) is used. However, NFS does not coordinate network locking and RMS record locks.


This version of NFS does not support byte-range locking. If a byte-range lock request is received, it is handled as a file lock request.

File locking is implemented using the Network Lock Manager (NLM) (also known remote procedure call, or RPC, lockd ) and the Network Status Monitor (NSM) (also known as RPC statd ). The NLM coordinates locks made by clients. The NSM recovers lock information in case the server or client fails. The NSM uses the NLM to keep the host list when the client or the server fails and reboots, as follows:

The NSM and the NLM are enabled if you select LOCKD/STATD in the TCPIP$CONFIG.COM configuration procedure. As a result, two processes are started when you start TCP/IP Services: TCPIP$LOCKD and TCPIP$STATD. The NLM can be configured with the following optional parameters:

To set these parameters, create or edit the following file:


22.14.1 File Locking Service Startup and Shutdown

The file locking services can be shut down and started independently of TCP/IP Services. This is useful when you change parameters or logical names that require the service to be restarted.

The following files are provided:

To preserve site-specific parameter settings and commands, create the following files. These files are not overwritten when you reinstall TCP/IP Services:

22.15 Improving NFS Server Performance

This section provides information to help you identify and resolve problems and tune system performance.

22.15.1 Displaying NFS Server Performance Information

The SHOW NFS_SERVER command displays information about the running NFS server. You can use the information to tune NFS server performance.

You can enter SHOW NFS_SERVER for a specific client or host if it is listed in the proxy database. The counter information can be especially useful in determining the load on your system.

For more information about the SHOW NFS_SERVER command, refer the HP TCP/IP Services for OpenVMS Management Command Reference.

22.15.2 Increasing the Number of Active Threads

The NFS server is an asynchronous, multithreaded process. This means that multiple NFS requests can be processed concurrently. Each NFS request is referred to as a thread. With increased server activity, client users may experience timeout conditions. Assuming the server host has the available resources (CPU, memory, and disk speed), you can improve server response by increasing the number of active threads. You do this by changing the value for the appropriate NFS server attributes, as described in Section 22.12.

The NFS server supports both TCP and UDP connections. You can control the maximum number of concurrent threads for each type of connection.

These attributes are not dynamically loadable. You must restart the NFS server in order to effect the changes. See Section 22.12 for more information.

Do not set the UDP maximum threads to zero. If you set the variable to zero, the protocol will be disabled.

If you increase the number of active threads, you should also consider increasing the timeout period on UNIX clients. You do this with the /TIMEOUT option to the TCP/IP Services MOUNT command.

If your clients still experience timeout conditions after increasing the number of active threads and the timout period on the client, you may need to upgrade your hardware.

22.15.3 Managing the File Name Cache

The NFS server caches the contents of directory files in addition to the content of other files. The server must access the directory files to cache them.

You can manage the performance of the NFS server using the following logical names:

In addition, you can also use the NFS sysconfig attribute ovms_xqp_plus_enabled to modify the behavior of the NFS server to take advantage of the directory and name caches. This attribute is specified as a bit mask. The default value is 0, or OFF.

The following list describes the mask values:

Obtain a combination of choices by adding the desired values. For example, enter 7 for a combination of the three.

When directory caching is enabled, the system must be configured to be able to handle the increased directory cache requirements. The following SYSGEN parameters may need to be increased, depending on the maximum number of files that the NFS server may access at any given time. This maximum is determined by the FILLM quota of the NFS$SERVER account and the SYSGEN parameter CHANNELCNT .

Use the MODPARAMS.DAT file and AUTOGEN to make the changes. Define the following parameters:

To calculate the PAGEDYN value, add the values of these parameters and multiply by 512.

22.15.4 OpenVMS SYSGEN Parameters That Affect Performance

The following OpenVMS SYSGEN parameters impact NFS server performance:

Previous Next Contents Index