xenapi: allowing for more than 2TB of ephemeral storage

Registered by John Garbutt on 2013-06-11

The VHD format has a 2TB disk size limit, however, you may wish to add more than 2TB of ephemeral space to a VM.

Note: the exact limit (due to overheads, etc) is around 2043 GB. Certain version on XenServer do not deal well with disks over that size, but under 2TB.

To do this, you can add several disks to a VM, that in total give the user the total ephemeral space they want. In guest, the user can use LVM or similar to aggregate those disks into a single volume.

In addition, which such large disks, we should allow admins to configure nova such that a partition is created on the disk, but no filesystem is created. Leaving the users free to do what they want with the space (or prehaps leaving cloud-init to configure the disks appropriately)

At the moment it is not practical to have root disks bigger than 2TB, so for now, we will assume those are smaller than 2TB, and only worry about "oversized" ephemeral disks.

Blueprint information

Status:
Complete
Approver:
Russell Bryant
Priority:
Medium
Drafter:
John Garbutt
Direction:
Approved
Assignee:
John Garbutt
Definition:
Approved
Series goal:
Accepted for havana
Implementation:
Implemented
Milestone target:
milestone icon 2013.2
Started by
Thierry Carrez on 2013-06-18
Completed by
Russell Bryant on 2013-07-12

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Gerrit topic: https://review.openstack.org/#q,topic:bp/xenapi-large-ephemeral-disk-support,n,z

Addressed by: https://review.openstack.org/32760
    xenapi: support ephemeral disks bigger than 2TB

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