MBR2GPT.EXE converts a disk from the Master Boot Record (MBR) to the GUID Partition Table (GPT) partition style without modifying or deleting data on the disk. The tool runs from a Windows Preinstallation Environment (Windows PE) command prompt, but can also be run from the full Windows 10 operating system (OS) by using the /allowFullOS option.
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The tool is available in both the full OS environment and Windows PE. To use this tool in a deployment task sequence with Configuration Manager or Microsoft Deployment Toolkit (MDT), you must first update the Windows PE image (winpe.wim, boot.wim) with the Windows ADK 1703, or a later version.
Offline conversion of system disks with earlier versions of Windows installed, such as Windows 7, 8, or 8.1 aren't officially supported. The recommended method to convert these disks is to upgrade the operating system to Windows 10 first, then perform the MBR to GPT conversion.
Using DiskPart, the current disk partition layout is displayed prior to conversion - three partitions are present on the MBR disk (disk 0): a system reserved partition, a Windows partition, and a recovery partition. A DVD-ROM is also present as volume 0.
If the existing MBR system partition can't be reused, a new ESP is created by shrinking the OS partition. This new partition has a size of 100 MB (or 260 MB for 4K sector size disks) and is formatted FAT32.
The conversion tool will attempt to remap all drive letter assignment information contained in the registry that corresponds to the volumes of the converted disk. If a drive letter assignment can't be restored, an error will be displayed at the console and in the log, so that you can manually perform the correct assignment of the drive letter.
These files contain errors and warnings encountered during disk validation and conversion. Information in these files can be helpful in diagnosing problems with the tool. The setupact.log and setuperr.log files will have the most detailed information about disk layouts, processes, and other information pertaining to disk validation and conversion.
You can also view the partition type of a disk by opening the Disk Management tool, right-clicking the disk number, clicking Properties, and then clicking the Volumes tab. See the following example:
If Windows PowerShell and Disk Management aren't available, such as when you're using Windows PE, you can determine the partition type at a command prompt with the DiskPart tool. To determine the partition style from a command line, type diskpart and then type list disk. See the following example:
This issue occurs because in Windows 10, version 1903 and later versions, MBR2GPT.exe requires access to the ReAgent.dll file. However, this dll file and its associated libraries are currently not included in the Windows PE boot image for Windows 10, version 1903 and later.
Note: The USB flash drive format must be FAT32 so that you are able to boot the system from USB flash drive. Here you can learn more about How to convert the USB flash drive format to FAT32.
Before booting the system from a USB flash drive or CD-ROM, please let your computer enters the BIOS configuration first, here you can learn more about How to enter BIOS configuration. After entering the BIOS configuration, there are two kinds of BIOS screen which are UEFI mode and Legacy mode, please refer to the following steps in order.
After updating to hardware version 18, some guest OS, such as CentOS 7, on AMD CPUs might fail with kernel panic when you boot the virtual machine. You see the kernel panic message when you open a web console for the virtual machine.
If an ESXi host of version 7.0 Update 2 is installed on a FCoE LUN and uses UEFI boot mode, when you try to upgrade the host by using vSphere QuickBoot, the physical server might fail with a purple diagnostic screen because of a memory error.
USB devices have a small queue depth and due to a race condition in the ESXi storage stack, some I/O operations might not get to the device. Such I/Os queue in the ESXi storage stack and ultimately time out. As a result, ESXi hosts become unresponsive. In the vSphere Client, you see alerts such as Alert: /bootbank not to be found at path '/bootbank' and Host not-responding. In vmkernel logs, you see errors such as: 2021-04-12T04:47:44.940Z cpu0:2097441)ScsiPath: 8058: Cancelled Cmd(0x45b92ea3fd40) 0xa0, cmdId.initiator=0x4538c859b8f8 CmdSN 0x0 from world 0 to path "vmhba32:C0:T0:L0". Cmd count Active:0 Queued:1. 2021-04-12T04:48:50.527Z cpu2:2097440)ScsiDeviceIO: 4315: Cmd(0x45b92ea76d40) 0x28, cmdId.initiator=0x4305f74cc780 CmdSN 0x1279 from world 2099370 to dev "mpx.vmhba32:C0:T0:L0" failed H:0x5 D:0x0 P:0x0 Cancelled from path layer. Cmd count Active:1 2021-04-12T04:48:50.527Z cpu2:2097440)Queued:4
You might see a slowdown of up to 60 min in the booting time of ESXi hosts after an upgrade to ESXi Update 2a. The issue does not affect updates to ESXi Update 2a from earlier versions of ESXi 7.0.x. The issue occurs only when you use a vSphere Lifecycle Manager image or baseline, or the esxcli software profile update command to perform the upgrade operation. If you use an ISO image or a scripted installation, you do not encounter the problem. The issue is most likely to affect iSCSI configurations, but is related to the ESXi algorithm for boot bank detection, not to slow external storage targets.
Certain deployment scenarios, such as cloning ESXi boot banks, might lead to partially of fully identical UUIDs of multiple ESXi hosts. Since UUIDs are used for VMFS heartbeat and journal operations, when you have duplicating UUIDS, after installation or upgrade operations multiple ESXi hosts might attempt to access metadata regions on the same VMFS datastore. As a result, you might see metadata corruption in some VMFS datastores. In the vmkernel logs, you see messages such as: vmkernel 608: VMFS volume DCS_HCFA_TEDS_Regulated_10032/5ba2905b-ac11166d-b145-0025b5920a02 on naa.60060e8012a34f005040a34f00000d64:1 has been detected corrupted. 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 319: FS3RCMeta 2245 200 21 105 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 326: 0 0 0 0 0 0 0 0 0 0 0 7 0 254 1 4 0 248 3 96 0 0 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 332: 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 338: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 346: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 346: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
If the USB host controller disconnects from your vSphere system and any resource on the device, such as dump files, is still in use by ESXi, the device path cannot be released by the time the device reconnects. As a result, ESXi provides a new path to the USB device, which breaks connection to the /bootbank partition or corrupts the VMFS-L LOCKER partition.
When you clone an ESXi boot device, you create instances with identical UUIDs. Since UUIDs are used for VMFS Heartbeat and Journal operations, when you have duplicating UUIDS, after installation or upgrade operations multiple ESXi hosts attempt to access metadata regions on the same VMFS datastore. As a result, you might see a massive metadata corruption in VMFS datastores on multiple ESXi hosts. In the vmkernel logs, you see messages such as: vmkernel 608: VMFS volume DCS_HCFA_TEDS_Regulated_10032/5ba2905b-ac11166d-b145-0025b5920a02 on naa.60060e8012a34f005040a34f00000d64:1 has been detected corrupted. 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 319: FS3RCMeta 2245 200 21 105 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 326: 0 0 0 0 0 0 0 0 0 0 0 7 0 254 1 4 0 248 3 96 0 0 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 332: 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 338: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 346: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2021-06-08T15:58:22.126Z cpu1:2097600)FS3: 346: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2ff7e9595c
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