After installing VERITAS Volume Manager for Windows , some installations report a high incidence of "Event ID 50: Lost Delayed Write" errors. It is important to point out that this is not a VERITAS issue. Viewing the error presented below, it is often assumed that the disk manager I/Odriver,  (vxio.sys),  is at fault..

 

The system file vxio is simply passing on what has been reported to it.

Th e"Lost Delayed Write" errors become evident when reviewing the system log file. A description of the event is as follows:
 

Event ID: 50

Event Type: Warning

Event Source: Disk

Description: {Lost Delayed-WriteData} The system was attempting to transfer file data from buffers to \Device\HarddiskVolume1. The write operation failed, and only some of the data may have been written to the file.

An actual message from a system log will be in this format:
"vxio Warning None50 N/A VRTSSVRQ {Lost Delayed-Write Data} The system was attempting to transfer file data from buffers to. The write operation failed, and only some of the data may have been written to the file."

"Lost Delayed Write"error messages indicate that the file system may be in an inconsistent state, as the file system metadata in the cache was not written to disk before a volume was dismounted. The messages do not always indicate that there is an error, just that the possibility exists. These errors are most often seen in a clustered environment where volumes are frequently brought online and offline. These errors are seen with BASIC and DYNAMIC disks.

Generally, delayed write errors can be triggered by two events:
 

1. The application does not stop issuing I/O within the specified time, specifically before Volume Manager is told by cluster to go offline.

 

2. The file system is in the process of flushing the file system cache when the volume is dismounted. The Windows cache manager periodically flushes the file system cache. A flush will also occur just before Volume Manager dismounts a volume.

Not all "Lost Delayed Write" errors have the same cause.

 

Possible solutions included
 

1. Update the firmware of the controllers and components of the system in question. "Lost Delayed Write"errors may occur on both SCSI attached and fibre attached systems.

 

2. Check the length of all external SCSI cables. If they exceed the recommended length, this error could happen. The length of the cable is determined by contacting the manufacturer of both the SCSI adapter and the cable manufacturer.

 

3. Ensure proper SCSI termination. Is it software-only termination or active hardware termination?

Contact the SCSI adapter manufacturer for best recommendations.

 

4. Heavy local file I/O to the disk can trigger the problem. In this case, check the SCSI controller's cache settings. Try adjusting the cache for 100% write or disable the cache altogether.

 

5. Heavy network I/O to the disk may also cause the "Lost Delayed Write" error.

Several Knowledge Base articles are available from Microsoft Corporation on this subject:
 

Microsoft Knowledge Base Article- Q252974

Error Message: System Process -Lost Delayed-Write Data

 

Microsoft Knowledge Base Article- Q293842

"Lost Delayed-Write Data" Error Message Under Extreme File System Stress

 

Microsoft Knowledge Base Article- Q272569

System Process Loses Delayed-Write Data with Windows Clustering

 

Microsoft Knowledge Base Article- Q304415

Support for Multiple Clusters Attached to the same SAN Device

 

Microsoft Knowledge Base Article- Q321733

A "Delayed Write Failed" Error Message Occurs When You Write a File to a Server