Initialization Overview

After you attach a new data disk to a server, you must initialize the disk including creating partitions, creating file systems, and mounting the partitions before you can use the disk.

Scenarios

System disk
When a server is created, a system disk is automatically initialized with Master Boot Record (MBR).
New data disk
- If a data disk is created together with a server, EVS automatically attaches it to the server. You only need to initialize it to make it available for use.
- If a data disk is created explicitly, you need to first attach it to a server and then initialize it.
For detailed operation instructions, see Table 1.
Existing data disk
An existing data disk is a disk created from a snapshot, a backup, or an image, or a disk detached from another server.
- You can choose not to re-partition the disk, but use the disk existing partitions.
  - In Linux, create new mount points and mount the partitions, and configure auto mount at system start.
  - In Windows, no further action is required. You can simply use the existing partitions.
- You can also re-initialize the data disk.
  Re-partitioning a disk will erase all the existing data on the disk, so you are advised to use snapshots to back up the disk data first.
  - In Linux, unmount the partitions, delete them (by running fdisk <disk-name>, entering d and the partition number, and entering w), and then re-initialize the disk.
  - In Windows, delete the partitions (using the volume deletion tool) and then re-initialize the disk.
  For detailed initialization operations, see Table 1.

Impact on the System

An initialization operation includes partitioning, which deletes all the data on the disk.
If you change the partition style of a disk, data on the disk will be erased. Select an appropriate partition style when initializing disks.
Initializing a disk does not delete the snapshots created for the disk, so you can still use snapshots to roll back data to the source disk after the disk is initialized.

Operation Instructions

Major initialization steps include creating partitions and file systems, mounting partitions, and configuring auto mount at system startup. In Linux, you can choose different partition styles based on your disk capacity. For details, see Table 2.

The maximum disk size that MBR supports is 2 TiB, and that GPT supports is 18 EiB. If your disk is greater than 2 TiB or you may expand it to over 2 TiB later, use GPT when initializing disks.

**Table 1** Disk initialization instructions
Disk Capacity	Partition Style	OS	Reference
Capacity ≤ 2 TiB	Guid Partition Table (GPT) or MBR	Linux	Initializing a Linux Data Disk (Less Than or Equal to 2 TiB)
Capacity ≤ 2 TiB	Guid Partition Table (GPT) or MBR	Windows	Initializing a Windows Data Disk
Capacity > 2 TiB	GPT	Linux	Initializing a Linux Data Disk (Greater Than 2 TiB)
Capacity > 2 TiB	GPT	Windows	Initializing a Windows Data Disk

Partition Styles

Common disk partition styles include MBR and GPT. In Linux, you can choose different partition styles based on your disk capacity, as described in Partition Styles.

**Table 2** Partition styles
Partition Style	Max. Disk Size Supported	Max. Number of Partitions Supported	Linux Partitioning Tool	Reference
MBR	2 TiB	MBR partitions include primary partitions and extended partitions. A maximum of four primary partitions are supported. If you need more partitions, create one extended partition. The following is an example: Four primary partitions Three primary partitions and one extended partition The extended partition must be divided into logical partitions before use. For example, to create six partitions, you can create them in the following two ways: Three primary partitions and one extended partition, with the extended partition divided into three logical partitions One primary partition and one extended partition, with the extended partition divided into five logical partitions For how to create logical partitions, see Creating a Logical Volume Using LVM.	fdisk parted	Initializing a Linux Data Disk (Less Than or Equal to 2 TiB) Initializing a Windows Data Disk
GPT	18 EiB 1 EiB = 1048576 TiB	Not limited GPT partitions are not categorized.	parted	Initializing a Linux Data Disk (Greater Than 2 TiB) Initializing a Windows Data Disk

Common EVS Device Names in Linux

The following lists some common EVS device names in Linux:

System disk: /dev/vda, /dev/sda, and /dev/xvda
Data disk: /dev/vd[b-z], /dev/sd[b-z], and /dev/xvd[b-z]
Examples: /dev/vdb, /dev/vdc, /dev/sdb, /dev/sdc, /dev/xvdb, and /dev/xvdc
Partition: /dev/vd[a-z][digit], /dev/sd[a-z][digit], /dev/xvd[a-z][digit]
Examples: /dev/vda1, /dev/vda2, /dev/vdb1, /dev/vdb2

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