After you attach a new empty data disk to an Elastic Compute Service (ECS) instance, you cannot directly use the disk to store data. To use the disk, you must initialize the disk. The initialization operations include partitioning the disk and mounting file systems on the disk. This topic describes the scenarios in which disks need to be initialized and how to initialize a disk. This topic also describes the partition formats and device names of disks.
Scenarios
You can initialize only the following new data disks that do not contain data:
Data disks that are created along with ECS instances that run Linux operating systems
Empty data disks that are separately created
You do not need to initialize system disks that are created along with ECS instances or data disks that are created along with ECS instances that run Windows operating systems. The system disks are automatically partitioned and file systems are automatically mounted to the system disks.
In most cases, a disk created from a snapshot contains data. In this case, you need to only
mountfile systems on the disk or bring the disk online. For more information, see Step 8 in the "Create a disk from a snapshot" topic.
Procedure
Determine whether a disk needs to be partitioned.
If you want to partition the disk, select an initialization method based on the size of the disk.
If you do not want to partition the disk, create a file system on the raw disk. This method is applicable only to Linux operating systems.
Select an initialization method based on the size of the disk.
Initialize a data disk whose size does not exceed 2 TiB
Operating system
Initialization tool
Partition format
Common file system
References
Linux
Partition: Parted
File system: e2fsprogs
GUID Partition Table (GPT) (recommended)
MBR
Ext4
XFS
Initialize a data disk whose size does not exceed 2 TiB on a Linux instance
Windows
Disk Management
GPT (recommended)
MBR
NTFS
Initialize a data disk whose size does not exceed 2 TiB on a Windows instance
Initialize a data disk whose size exceeds 2 TiB
Operating system
Initialization tool
Partition format
Common file system
References
Linux
Partition: Parted
File system: e2fsprogs
GPT
Ext4
XFS
The Initialize a data disk whose size exceeds 2 TiB on a Linux instance section in the "Initialize a data disk whose size exceeds 2 TiB" topic
Windows
Disk Management
GPT
NTFS
The Initialize a data disk that is larger than 2 TiB on a Windows instance section in the "Initialize a data disk whose size exceeds 2 TiB" topic
Partition formats
Data disks support the MBR and GPT partition formats. The following table describes the differences between the two partition formats.
Partition format | Maximum partition size | Number of partitions | Description |
MBR | 2 TiB | An MBR disk can have one of the following groups of partitions:
| MBR partitions are classified into primary, extended, and logical partitions. |
GPT | 18 EiB (1 EiB = 1,048,576 TiB) Note An Alibaba Cloud GPT disk can be up to 32 TiB in size. |
| All partitions are primary partitions. No extended partitions or logical partitions exist. |
An MBR partition can be up to 2 TiB in size. A GPT partition can be up to 18 EiB in size. If your data disk is larger than 2 TiB in size or if you may need to resize your data disk to larger than 2 TiB, you must use the GPT partition format.
Device names of data disks on Linux instances
By default, data disks that are attached to Linux instances are automatically assigned device names based on the following naming conventions:
I/O optimized instance:
The device names of data disks that are attached by using the Non-Volatile Memory Express (NVMe) protocol are in the /dev/nvmeXn1 format. Examples: /dev/nvme1n1, /dev/nvme2n1, and /dev/nvme3n1. For information about disks that support the NVMe protocol, see NVMe disks.
The device names of data disks that are attached by using protocols other than the NVMe protocol are in the /dev/vd[b-z] format. Examples: /dev/vdb, /dev/vdc, and /dev/vdd.
Non-I/O optimized instances: The device names of data disks that are attached to non-I/O optimized Linux instances are in the /dev/xvd[b-z] format. Examples: /dev/xvdb, /dev/xvdc, and /dev/xvdd.