By Dervish / Last Updated March 9, 2022


Dynamic disk offline case study

"Dynamic Disk offline on Windows 2000 Server SP4"

I have one Server IBM System X3650 configure with Windows 2000 Server Sp4. 4 HDDs attached with that Server and have two Array of RAID 1. Disk 0 configure as Basic disk and Disk 1 configure as Dynamic disk. Each time the Server reboot Disk 1 will become offline. Is there any idea to solve? I have already edited the registry and change the dmboot start value to 0. But the problem still persists each time the Server reboot.

What causes dynamic disk offline?

When a dynamic disk is inaccessible, an error icon "Offline" appears on the dynamic disk. The message indicates dynamic disk may be corrupted or intermittently unavailable. Sometimes the disk name will change to "Missing" while the "Offline" status occurs. Such alteration states the dynamic disk was recently available on the system but can not be located or identified anymore. The missing disk may be corrupted, powered down, or disconnected. The two causes below is common reasons why dynamic disk offline.

Cause1: Controller driver is not started at boot

In the event that the driver for the second mass storage controller is not set to start at boot, the devices under the controller may be unavailable to use after system has started. In the built-in Disk Management, the dynamic disks may show up as "Offline".

Cause 2: Extend Hardware RAID Array

As is known to us all dynamic disks contain a database at the end of the physical disk. The Logical Disk Manager, or LDM for short, keeps track of where the current database is located. And a backup LDM header will record a pointer to the database when the disk is first converted to dynamic. Extending a hardware RAID array may cause the relocation of the present database to not work because an erroneous attempt to move the old obsolete database is made (which may have already been partially or completely overwritten with user data) to the end of the new physical disk.

How to bring a dynamic disk that is offline and missing back online

Repair any disk, controller, or cable problems and make sure that the physical disk is turned on, plugged in, and attached to the computer.

Solution 1: To reactivate a dynamic disk with Disk Management

In snap-in Disk Management, right click the dynamic disk displays missing or offline and select "Reactivate Disk". The dynamic disk should be shown as "Online" after reactivation.

Solution 2: To online a disk using CMD

Step1: Open a command prompt and type "diskpart". In the command-line interface, type "list disk" to display all disks.

Note: Missing disks are numbered M0, M1, M2, and so on, and offline disks are numbered 0, 1, 2, and so on.

Step2: Type "select disk number" and hit Enter.

Step 3. Type "online" and hit Enter. 

Online Disk CMD

Tips: For Windows 2000, you need to download the diskpart command prompt utility.

If you want to convert dynamic disk into basic without losing data, you can use AOMEI Partition Assistant Server

Convert Dynamic Disk to Basic