Attaching an Existing Shared Disk

Scenarios

This section describes how to attach an existing shared disk to a server to be used as a data disk.

Notes and Constraints

If you simply attach a shared disk to multiple servers, files cannot be shared among them. Because there are no mutually agreed data read/write rules among them, read and write operations from them may interfere with each other, or unpredictable errors may occur. To share files between the servers, set up a shared file system or a clustered management system first.

• A shared disk can be attached to a maximum of 16 servers. These servers and the shared disk must be in the same AZ of a region.
• A shared, In-use disk can only be attached to servers when the maximum number of servers that the disk can be attached to has not been reached.
• A shared disk can only be attached to servers running the same type of OS (either Windows or Linux).

  For example, if you attach a shared disk to multiple Windows servers and then detach it, the shared disk cannot be attached to Linux servers later. This is because Windows and Linux support different file systems. Improper operations may damage the original file system.

• A shared disk can only be used as a data disk. It cannot be used as a system disk.
• Cloud servers created from ISO images are only used for OS installation. They have limited functions and cannot have EVS disks attached.
• A server must be in the Running or Stopped state before disks can be attached to it.
• A frozen disk cannot be attached.
• A detached, yearly/monthly system disk purchased together with a server can be re-attached to be used as a data disk for any server. If you want to use it again as a system disk, you must attach it to the original server.
• A detached, pay-per-use system disk purchased together with a server can be re-attached to be used as a data disk for any server. If you want to use it again as a system disk, you must attach it to a server that uses the same image as the original server.

Procedure

1. Log in to the management console.
2. Click in the upper left corner and choose Storage > Elastic Volume Service.

   The Elastic Volume Service page is displayed.

3. In the disk list, locate the disk and click Attach.
   • Shared disks support batch attachment, so you can attach a shared disk to multiple servers. In the Attach Disk dialog box, the left area shows the server list. After you select the target servers, they will be displayed in the right area.
   • A shared disk can only be attached to servers when the disk status is Available or In-use.

4. Select servers to attach the disk. Ensure that the disk and servers are in the same AZ. After you select servers, the system automatically inputs Data disk as the disk function.

   One device name can be used for one disk only. If a device name has been used, it will no longer show up in the drop-down list and cannot be selected.

   Figure 1 Attach Disk
   

5. Click OK to go back to the disk list page.

   The status of the disk is Attaching, indicating that the disk is being attached to the server. When the disk status changes to In-use, the disk has been attached.

6. (Optional) Mount the existing disk partition on a mount point if you are attaching the disk to Linux servers. The mount command is as follows:

   mount Disk partition Mount point

Helpful Links

To find out why your disk cannot be attached, see Why Can't I Attach My Disk to a Server?

To check out more attachment FAQs, see Attachment.