Microsoft KB Archive/165840

= Using Stripe Set During Initialization May Result in Data Loss =

Article ID: 165840

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q165840



SUMMARY
You can create software RAID 5 stripe sets with parity partitions in Windows NT Server.

RAID 5 stripe sets consist of striping data with parity information across multiple drives in 64KB stripes. During the initialization stage of creating the stripe set with parity, Windows NT Server calculates the parity information for each 64KB stripe.

You are not inhibited by Windows NT Disk Administrator from formatting the stripe set and then immediately using the volume while initialization is still in progress. Windows NT Server also does not inhibit you from using a volume that is being recovered during regeneration after a drive failure. This is because the FTDISK driver makes sure that all changes made to the disk are mirrored in the parity block. The driver takes care of all synchronization problems including the writing of the data catching up with the initialization of the parity.

However, while the volume is initializing or regenerating, it is "exposed"; in other words, if a drive failure occurs while the stripe set with parity is initializing, you will lose your entire set. It is only after the stripe set is initialized that you have any fault tolerance. The same process occurs with bad sectors. Sector sparing is not enabled until after initialization is complete.

If you choose to use the volume during initialization or regeneration, you run the risk of losing any and all data on the volume if in the event the initialization process fails. Because of this, Microsoft recommends waiting for a complete initialization or regeneration of the stripe set before you use it to ensure the protection and integrity of your data.



MORE INFORMATION
The Event Viewer will contain events reporting when the stripe set starts initialization, completes initialization, or fails initialization.

  Event ID: 16 Source: FTDISK Description: Synchronization of a stripe with parity set started.

Event ID: 20 Source: FTDISK Description: Synchronization of a stripe with parity set is complete.

Event ID: 24 Source: FTDISK Description: Synchronization of a stripe with parity failed.

For additional information, please see the following articles here in the Microsoft Knowledge Base:

ARTICLE-ID: 135061

TITLE: Regeneration of a Stripe Set With Parity Disk Fails

Additional query words: SS generate

Keywords: kbsetup KB165840

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