NetBackup Client Performance

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Evaluating System Components

In addition to evaluating NetBackup's performance, you should also verify that common system resources are in adequate supply. You may want to use the Windows Performance Monitor utility included with Windows NT or Windows 2000. For information about using the Performance Monitor, refer to your Microsoft documentation.

The Performance Monitor organizes information by object, counter, and instance.

An object is a system resource category, such as a processor or physical disk. Properties of an object are counters. Counters for the Processor object include %Processor Time, which is the default counter, and Interrupts/sec. Duplicate counters are handled via instances. For example, to monitor the %Processor Time of a specific CPU on a multiple CPU system, the Processor object is selected, then the %Processor Time counter for that object is selected, followed by the specific CPU instance for the counter.

When you use the Performance Monitor, you can view data in real time format or collect the data in a log for future analysis. Specific components to evaluate include CPU load, memory use, and disk load.

Monitoring CPU Load

To determine if the system has enough power to accomplish the requested tasks, monitor the % Processor Time counter for the Processor object to determine how hard the CPU is working, and monitor the Process Queue Length counter for the System object to determine how many processes are actively waiting for the processor.

For % Processor Time, values of 0 to 80 percent are generally considered safe. Values from 80 percent to 90 percent indicate that the system is being pushed hard, while consistent values above 90 percent indicate that the CPU is a bottleneck.

Spikes approaching 100 percent are normal and do not necessarily indicate a bottleneck. However, if sustained loads approaching 100 percent are observed, efforts to tune the system to decrease process load or an upgrade to a faster processor should be considered.

Sustained Processor Queue Lengths greater than two indicate too many threads are waiting to be executed. To correctly monitor the Processor Queue Length counter, the Performance Monitor must be tracking a thread-related counter. If you consistently see a queue length of 0, verify that a non-zero value can be displayed.

The default scale for the Processor Queue Length may not be equal to 1. Be sure to read the data correctly. For example, if the default scale is 10x, then a reading of 40 actually means that only 4 processes are waiting.

Monitoring Memory Use

Memory is a critical resource for increasing the performance of backup operations. When you examine memory usage, view information on:

  • Committed Bytes. Committed Bytes displays the size of virtual memory that has been committed, as opposed to reserved. Committed memory must have disk storage available or must not require the disk storage because the main memory is large enough. If the number of Committed Bytes approaches or exceeds the amount of physical memory, you may encounter problems with page swapping.

  • Page Faults/sec. Page Faults/sec is a count of the page faults in the processor. A page fault occurs when a process refers to a virtual memory page that is not in its Working Set in main memory. A high Page Fault rate may indicate insufficient memory.

Monitoring Disk Load

To use disk performance counters to monitor the disk performance in Performance Monitor, you may need to enable those counters. Windows may not have enabled the disk performance counters by default for your system.

For more information about disk performance counters, from a command prompt, type:

 diskperf -help 

To enable these counters and allow disk monitoring:

  1. From a command prompt, type:

     diskperf -y 

  2. Reboot the system.

To disable these counters and cancel disk monitoring:

  1. From a command prompt, type:

     diskperf -n 

  2. Reboot the system.

When you monitor disk performance, use the %Disk Time counter for the PhysicalDisk object to track the percentage of elapsed time that the selected disk drive is busy servicing read or write requests.

Also monitor the Avg. Disk Queue Length counter and watch for values greater than 1 that last for more than one second. Values greater than 1 for more than a second indicate that multiple processes are waiting for the disk to service their requests.

Several techniques may be used to increase disk performance, including:

  • Check the fragmentation level of the data. A highly fragmented disk limits throughput levels. Use a disk maintenance utility to defragment the disk.

  • Consider adding additional disks to the system to increase performance. If multiple processes are attempting to log data simultaneously, dividing the data among multiple physical disks may help.

  • Determine if the data transfer involves a compressed disk. The use of Windows NT compression to automatically compress the data on the drive adds additional overhead to disk read or write operations, adversely affecting the performance of NetBackup. Only use Windows NT compression if it is needed to avoid a disk full condition.

  • Consider converting to a system based on a Redundant Array of Inexpensive Disks (RAID). Though more expensive, RAID devices generally offer greater throughput, and, (depending on the RAID level employed), improved reliability.

  • Determine what type of controller technology is being used to drive the disk. Consider if a different system would yield better results. The following table shows some typical throughput rates for common controllers:

CONTROLLER TECHNOLOGY

MAX TRANSFER RATE

# DEVICES

BIOS Hard disk (MFM, RLL, ESDI)

8MB/s

2

IDE

5MB/s

2

SCSI

5MB/s

7

SCSI-2 Fast

10MB/s

7

SCSI-2 Wide

20MB/s

7

SCSI-2 F/W

40MB/s

7

Ultra SCSI

80MB/s

15



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Implementing Backup and Recovery(c) The Readiness Guide for the Enterprise
Implementing Backup and Recovery: The Readiness Guide for the Enterprise
ISBN: 0471227145
EAN: 2147483647
Year: 2005
Pages: 176

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