JSI Tip 7752. When you use Device Manager to scan for hardware changes in Windows Server 2003, devices displayed as Online in Disk Management disappear?

The subject behavior will occur if a SCSI hard disk that is identified as LUN 0 is offline when Device Manager scans.

When a scan fails on LUN 0 of a Target ID, Windows Server 2003 marks all LUNs in that Target ID as missing. Plug and Play then uses a Device Relations query to remove all the hard disks on that Target ID.

NOTE: This behavior is specified in the SCSI specification.