For a write-intensive server, the following procedures can improve the speed of disk writes.
You can increase the speed and efficiency of disk cache writes by increasing the number of write requests that can be executed at one time.
To determine whether you need to increase the number of concurrent writes, first compare the number of dirty cache buffers to the total number of cache buffers. These statistics are found on the General Information screen in MONITOR. Dirty cache buffers contain data that has not yet been written to disk.
The ratio of dirty cache buffers to total cache buffers is an indicator of the efficiency of disk cache writes. If the number of dirty cache buffers is greater than 70 % of total cache buffers, increase the number of concurrent write requests.
For an explanation of file caching, see Setting the Cache Buffers in the Novell Storage Services Administration Guide.
NOTE: Increasing the number of concurrent disk cache writes slows disk cache reads. You might want to balance the speed of disk writes and reads to meet the needs of users. If your server's processing load is write-intensive, you can favor disk writes. If it is read-intensive, favor disk reads.
From the MONITOR Available Options, select Server Parameters > File Caching. For instructions on using MONITOR, see MONITOR in Utilities Reference.
NOTE: You can also set file caching parameters with the SET command in MONITOR.
Increase the value of Maximum Concurrent Disk Cache Writes.
If the parameter is currently at the default value of 50, try increasing it to 100. The changed value is now persistent.
Press Esc until you return to Available Options.
Use this procedure if network users frequently make many small write requests and the server is slow to respond to the requests.
From the MONITOR Available Options, select Server Parameters > File Caching. For instructions on using MONITOR, see MONITOR in Utilities Reference.
NOTE: You can also set file caching parameters with the SET command in MONITOR.
Increase the value of Dirty Disk Cache Delay Time.
This parameter specifies how long the system waits before writing a not-completely-dirty cache buffer to disk.
If the value is low, the system writes to disk more frequently, but writes fewer requests each time. If the value is high, the system waits longer before writing to disk, but executes more write requests with each operation. A higher value provides greater efficiency in writing to disk.
If the parameter is currently at the default value of 3.3 seconds, try increasing the value to 7 seconds.
Press Esc to return to the list of parameter categories and then select Directory Caching.
A list of Directory Caching Parameters appears in the upper window.
The scroll thumb to the right indicates that you can use the arrow keys to scroll the list.
Increase the value of Dirty Directory Cache Delay Time.
This parameter specifies how long the system keeps a directory table write request in memory before writing it to disk.
IMPORTANT: Increasing the parameter provides slightly faster performance, but can increase the chance of directory tables becoming corrupted.
If the parameter is currently at the default value of 0.5 second, try increasing the value to 2 seconds.
Increase the value of Maximum Concurrent Directory Cache Writes.
This parameter determines how many write requests from directory cache buffers are executed at one time. Increasing this value increases the efficiency of directory cache write requests.
NOTE: Increasing the number of concurrent directory cache writes decreases the speed of directory cache reads. Balance the speed of writes and reads to meet the needs or your users.
If the parameter is currently at the default value of 10, try increasing the value to 25. The changed value is now persistent.
Press Esc until you return to Available Options.
Read-After-Write Verify is almost always provided by the hard disk. If your hard disk provides read-after-write verification, you might want to disable the software version of read-after-write verification in order to nearly double the speed of disk writes.
WARNING: Turning off read-after-write verification can increase the risk of data corruption on the server's hard disk. You should use the following procedure only if your disks provide read-after-write verification and are reliable or if your disk subsystem provides data fault tolerance through mirroring or appropriate RAID level.
From the MONITOR Available Options, select Storage Devices.
A list of Registered Storage Objects appears. The device information associated with a highlighted storage device appears in the upper window. You can verify the type of storage device in the Device Type field.
Select the desired hard disk from the list.
The Drive Status window appears. The Read After Write Verification field indicates whether the feature is turned On or Off.
Press Enter to access the Read After Write Verification options.
To change Read After Write Status, select Disable Verify.
Press Esc to return to Available Options.
NOTE: You can also disable read-after-write verification by setting the Enable Disk Read After Write Verify SET parameter to OFF. However, this setting affects only those disks loaded after the parameter value is changed. It does not change the setting for currently loaded disks.