Preparing a new disk in Windows Server: Get-Disk through Format-Volume, and why it starts offline

Goal

Take a raw or newly attached disk from unrecognized to a mounted, usable NTFS or ReFS volume using the Storage PowerShell module, and grow an existing volume safely afterward.

Prerequisites

Local administrator rights; the Storage module (built in); for a SAN-attached disk, awareness that the operating system's SAN policy — not a fault — may be why the disk does not appear ready.

Steps

1. List disks and their state: Get-Disk | Select-Object Number, FriendlyName, OperationalStatus, PartitionStyle, IsOffline, IsReadOnly. A newly presented SAN or virtual disk commonly shows IsOffline: True or IsReadOnly: True — the operating system's SAN policy (on Windows Server typically offlineShared, which leaves disks on a shared bus such as SCSI or iSCSI offline and read-only; the default can differ by edition or image) intentionally keeps such disks offline until an administrator brings them online, to avoid two hosts writing to the same disk at once. Read the current policy with Get-StorageSetting | Select-Object NewDiskPolicy or san inside diskpart.
2. Bring a disk online and writable only after confirming it is not shared with another host that also expects to own it: Set-Disk -Number 2 -IsOffline $false; Set-Disk -Number 2 -IsReadOnly $false.
3. Initialize a new disk with a GPT partition table (MBR is legacy and size-limited): Initialize-Disk -Number 2 -PartitionStyle GPT.
4. Create a partition using all remaining space: New-Partition -DiskNumber 2 -UseMaximumSize -AssignDriveLetter; the output shows the letter actually assigned (E below is an example).
5. Format it: Format-Volume -DriveLetter E -FileSystem NTFS -NewFileSystemLabel "Data" -Confirm:$false. -Confirm:$false suppresses the interactive prompt for unattended use.
6. To grow a volume later (after enlarging the underlying disk, rescan with Update-HostStorageCache), check how far it can actually extend first: Get-PartitionSupportedSize -DriveLetter E, then Resize-Partition -DriveLetter E -Size <value from SizeMax>.

Expected result

Get-Volume -DriveLetter E shows the new volume mounted, formatted, and healthy; a subsequent Resize-Partition succeeds up to the value Get-PartitionSupportedSize reported.

Limits and test basis

Get-Disk, Initialize-Disk, New-Partition, Format-Volume, Resize-Partition, and Get-PartitionSupportedSize are documented Storage module cmdlets; the DiskPart san command's policy values (onlineAll, offlineAll, offlineShared) and their offline/read-only effects are documented in Microsoft's command reference, which does not state the per-edition default — read it on the host instead of assuming it. There is no undo for Format-Volume beyond restoring from a backup — it destroys existing data on the target partition, so confirm the disk number and drive letter with Get-Disk/Get-Partition immediately before running it. None of these steps require a reboot; a drive letter becomes usable immediately.