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Windows 2003 operating systems (32- or 64-bit versions and all editions) can have stability issues when running any heavy I/O-based applications. SAS Technical Support has encountered this behavior at several customer sites on Windows 2003 operating systems that are running SAS applications with heavy I/O activity.

Because SAS is typically a heavy I/O-based application, it is very important to be aware of this issue when you deploy SAS on Windows 2003 where I/O is a critical component of the system requirements.

Problem Details

Under some situations, when a Windows 2003 system is under heavy I/O load, the Windows file cache can become flooded and your SAS job can fail with an I/O error message such as the following:

This message occurs on both Windows 2003 32-bit and 64-bit systems.

This error message might take longer to manifest itself on Windows 64-bit systems due to the larger memory footprint of the 64-bit platform, but it still does occur.

If you do get a storage error message and are unable to determine its cause, work with SAS Technical Support to help diagnose the source of the error.

Due to the nature of the problem and its causes, it is difficult to reproduce and predict when a system will encounter this behavior. This unpredictability makes it difficult to also define an exact definition for "heavy I/O." Some systems that are under large I/O workloads do not encounter this problem, while others encounter it under lighter I/O conditions. It has been noted that this error is more common with faster disk subsystems and hard drives that are typically found on SAN-based file systems.

Suggestions and Supporting Notes

• Get the latest STORPORT hardware drivers for your Host Bus Adaptors related to your storage. Newer drivers might alleviate or eliminate the issue. See SAS Note 35933 "On Windows Server 2003, the error message "ERROR: An I/O error has occurred on file libname.setname.DATA" displays in the SAS^® log."

  Most storage vendors are aware of this behavior and have been updating their drivers to help with the problem.

  Details of this issue are related to the interaction of the Microsoft STORPORT API and the HBA vendor’s driver code. The interaction can lead to resource exhaustion (memory) in the Windows 2003 kernel.

• Once the above error message has occurred, you need to reboot the Windows 2003 system. It might be necessary to reboot your Windows 2003 system at least weekly, sometimes as often as daily, depending on how frequently you encounter this I/O error message.

  Rebooting the system periodically clears out the file cache. This is important because the file cache is not being properly maintained by the operating system.

• Using the SAS SGIO option to force SAS to utilize direct I/O seems to overcome the problem. However, this setting can result in significant performance reduction due to file cache elimination. For more information on SGIO, see SAS Note 13636 "Achieving Better I/O Throughput Using SGIO in the Microsoft Windows Environment."
• Spread out multiple I/O intensive tasks by running the tasks at different times of the day with a scheduler or load-balancing mechanism like Platform LSF.
• Slowing down the I/O throughput from your storage device to your Windows computer also seems to overcome the problem. Again, there is a side-effect of poor SAS performance due to the reduced I/O throughput rate.
• Improved messages in the SAS logs for SAS 9.2 are more specific about different errors, therefore, should make it easier to diagnose your exact I/O error.
• Always seek out the latest updates on support.microsoft.com on this or related I/O errors.

Operating System and Release Information