Novell NETWARE 6-DOCUMENTATION Manual page 2545

Field
Dirty Cache Buffers
Long Term Cache Hits
Current Disk Requests
Explanation
Number of cache buffers that contain updated data that has not yet
been written to disk. The operating system writes the data to disk
either as soon as the cache buffer is filled or else when the Dirty
Disk Cache Delay Time elapses (default 3.3 seconds).
The trade-off is between allowing small writes to wait the delay time
or reducing the delay time and performing two writes. See
Disk Reads and Improving Disk Writes
and Storage Devices Guide. Also, see SET
Parameters for the Traditional File System" on page 232
description of the parameter that controls the delay time.
If the number of dirty buffers is frequently above 50% of Total Cache
Buffers, install more RAM for cache.
A disk I/O bottleneck may be indicated if the number of dirty buffers
remains constant and the number of Current Disk Requests remains
high. Consider installing a faster hard disk and controller.
Cumulative percentage of requests for disk blocks that were already
in cache.
Use this value to assess overall disk cache utilization. If this value
falls below 90%, install more RAM for cache.
Another field to check as you assess RAM is LRU Sitting Time. See
Tuning File Cache in the Server Memory Administation Guide.
Number of pending disk I/O requests that are queued for service.
Use this value as a measure of the system load for the disk channel.
If this number is consistently high, the disk and controller may be too
slow.
If the number of Dirty Cache Buffers exceeds 50% of Total Cache
Buffers and server performance is slow, consider installing faster
hard disks.
Improving
in the NetWare Server Disks
"File Caching
for
Utilities 107