Compressed Files

WARNING:  SBCON and file compression should not be run simultaneously. Because the default time for both delayed SBCON sessions and compression is midnight of the current day, change one of these defaults to another time immediately.

If you want to perform a delayed backup that includes files flagged for compression, schedule the delayed backup after the compression time to allow time for the compression to be completed.

When a NetWare 6 volume is mounted, file compression is set to On by default. When you perform a backup, you can specify whether to keep already compressed files in a compressed state for the backup, or back them up in a decompressed state.

To help you make a decision about whether to compress or decompress your backed up data, follow these guidelines:

• Backups are faster if files already compressed are left compressed.
• Compression is not supported in some environments (such as a NetWare 3.11 server, a DOS workstation, or Novell Storage Services^TM). If you intend to restore a file that is currently compressed to an environment that does not support compression, back it up in a decompressed state.
• The SBCON utility has no compression feature, so it cannot compress a file that is currently decompressed.
• If volume compression is turned on and you back up compressed files in a decompressed state, restore speed is degraded if you overwrite existing files.

  To improve restore speed, delete the files you no longer want from the hard disk before restoring them from the backup media. If you back up compressed files in a compressed state, restore speed is not affected.

• You might run out of disk space if you restore decompressed files to a volume that compresses files.

Host Server Performance

The speed of the SBCON utility depends upon the configuration of the host server and whether the server is backing up its own data or that of another server or workstation.

For information on server configuration and setting parameters, see Communications Parameters and File Caching Parameters under SET in NetWare Utilities Reference.

A server backing up its own data runs about twice as fast as a server backing up data from another server.

This section includes four options using LOAD and SET commands that can enhance your host server's performance.

Setting Minimum Packet Receive Buffers

Packet receive buffers represent the space in the server memory dedicated to handling network traffic. If the buffers are set too low, the server performance may be degraded.

To reset the packet receive buffers at the server console prompt, include the following SET command in the STARTUP.NCF file:

SET MINIMUM PACKET RECEIVE BUFFERS = X

The x represents the number of buffers. Set two buffers for each user on the system. The minimum is 10. The changes will take effect immediately.

Setting Reserved Buffers Below 16 MB

If your storage device driver requires memory below 16 MB and the server has more than 16 MB available to it, you must reserve memory below 16 MB for the driver.

To change the reserve memory at the server console prompt, include the following command in the STARTUP.NCF file:

SET RESERVED BUFFERS BELOW 16 MEG=X

Replace the x with a number between 8 and 300. The default is 200.

Setting Maximum Subdirectory Level and Minimum Cache Buffers

If you change the maximum subdirectory level in the server's STARTUP.NCF file, you must also change the minimum cache buffer. The default maximum subdirectory level is 25.

To change the cache buffers at the server console prompt, include the following commands in the AUTOEXEC.BAT file:

SET MINIMUM FILE CACHE BUFFERS=X

SET MAXIMUM DIRECTORY CACHE BUFFERS=X

This command changes the minimum and maximum directory in MONITOR > Available Options > Server Parameters. The changes will take effect immediately.