avanti technology, inc. (Network Management Tips)

Optimizing NetWare Server File System I/O
(NetWare v5.0 and later)

NetWare has long been recognized as the premiere file and print Server platform. Still, as with all good things, there is always room for improvement. Fortunately, Novell incorporated tuning capabilities into the NetWare, as well as some internal logic which attempts to tune the Server based upon loads which are encountered. The self-tuning feature can be a double edged sword since the heaviest load most typically encountered by a NetWare Server is during Backup. And while having the Server tune itself for better Backup performance may not seem so bad, it is not typical of normal production loads for which a Server spends most of its time and really needs to be tuned.

In this document, we'll suggest some tips which can be used to better tune the Server, not only for normal performance but also to enhance Backups. We'll also identify some parameters which can be manipulated prior to Backup to improve performance then restored to levels more appropriate for typical production activities.

SET Parameters for General Optimization
The following SET Parameter adjustments are suggested to improve overall File System performance:

Common File System (NW v6.0 / 6.5)


    SET Maximum Concurrent Directory Cache Writes = 500

Note: Default value is based on older, slower disk technology. Reference: Novell TID 10065644

Traditional File System (NW v6.0 / 6.5)


    SET Maximum Directory Cache Buffers = 4000

Reference: Novell TID 10012765 & Novell TID 10021744

SET Minimum Directory Cache Buffers = 2000
Reference: Novell TID 10012765 & Novell TID 10021744

SET Directory Cache Allocation Wait Time = 0.5 Sec
Reference: Novell TID 10012765 & Novell TID 10021744

Disk


    SET Enable Disk Read After Write Verify = OFF

Note: ON forces NetWare to re-read data after each write for verification. Redundant since most Disk Drives have this feature built-in.

SET Enable Hardware Write Back = ON
Note: If supported by installed Disk Drive(s), this caching / performance feature can improve performance.

SET Sequential Elevator Depth = 2000
Note: Default value is based on older, slower disk technology. Reference: November 2001 Novell AppNote

Traditional File System (NW v6.0 / 6.5)


    SET Maximum Concurrent Disk Cache Writes = 2000

Note: Default value is based on older, slower disk technology. Reference: Novell TID 10065644

NSS


    SET NSS Cache Balance Percent = 85

Reference: Novell TID 10012765 & Novell TID 10065215

SET Parameters for Backup Optimization
The following SET Parameter adjustments can be made before starting Backup and the restored afterwards to improve overall Backup performance:

Traditional File System (NW v6.0 / 6.5)


    SET Dirty Directory Cache Delay Time = 0.5 Sec

Reducing this value to 0.1 Sec allows changes to directory entries to be flushed more efficiently, helping reduce the number of Directory Cache Buffers typically required by Backup operations.

SET Directory Cache Buffer NonReferenced Delay = 5.5 Sec
Reducing this value to 0.1 Sec allows Directory Cache Buffers to be re-used more efficiently, helping reduce the number of Directory Cache Buffers typically required by Backup operations.

File Caching (NW v5.0 / 5.1)
Traditional File System (NW v6.0 / 6.5)


    Read Ahead LRU Sitting Time Threshold = 10 Sec

Reducing this value to 1 Sec allows more efficient Read Ahead operations during heavy file system operations, helping improve the efficiency of Cache Buffer operations typically required by Backup operations.

These adjustments can be done with a script either launched using the Backup software Pre and Post processing options or as a schedule task.

After making any of the recommended changes to the SET Parameters, always be sure to issue the FLUSH CDBE command at the Server System Console prompt to save the changes to the NetWare Registry.

This document is copyright © 2006 by avanti technology, inc.
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