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Limited Disk Throughput from Windows with BusLogic Adapter Causes Performance Problems

Details

Applications run slowly on my Windows virtual machine, even though I have tried typical troubleshooting procedures to fix the problem, like increasing RAM in the guest operating system and making sure there is enough space allocated for my virtual disk. What else can I try?

Solution

When you use the BusLogic virtual adapter with some versions of Windows running in a virtual machine, Windows issues only enough I/O to fill a queue depth of one. This limits disk throughput, which can cause some programs to run slowly and may result in other performance issues on your Windows guest operating system.

This behavior has been observed in the following Windows operating systems:

Windows 2000 Service Pack 3 (Service Pack 4 does not exhibit this problem.)
Windows 2003 Standard and Enterprise Editions
Windows XP

The issue may exist in other, untested versions of the Windows operating system as well.

To avoid this problem, use one of the following workarounds:

Use the device manager in Windows to scan for new devices. This allows Windows to use the correct queue depth, which improves system performance.
Use the LSI Logic virtual adapter instead of the BusLogic one. For locations on LSI Logic's Web site for downloading drivers, see www.vmware.com/support/kb/enduser/std_adp.php?p_faqid=1306.

Keywords

1890; iometer; qdepth; performance

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KB Article: 1890
Updated: Aug 14, 2009

Products:
VMware ESX
Product Versions:
VMware ESX 2.5.x
VMware ESX 3.0.x
VMware ESX 3.5.x

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