Citrix Systems Understanding NetApp Delete Snapshot, Reclaim Space, and VDI Coalescing in XenServer

to the SR. The corresponding PBD must be unplugged and re-plugged for the scheduler parameter to take effect. The disk scheduler can be adjusted using the following command:

xe sr-param-set other-config:scheduler=noopcfqanticipatorydeadline \

uuid=<valid_sr_uuid>

Note:

This will not effect EqualLogic, NetApp or NFS storage.

Automatically Reclaiming Space When Deleting Snapshots

When deleting snapshots with XenServer 6.0, all allocated space allocated on LVM-based SRs is reclaimed automatically and a VM reboot is not required; this is referred to as Online Coalescing.

Note:

Online Coalescing only applies to LVM-based SRs (LVM, LVMoISCSI, and LVMoHBA), it does not apply to EXT or NFS SRs, whose behaviour remains unchanged.

In certain cases, automated space reclamation may be unable to proceed, in these cases it is advisable to use the Off Line Coalesce tool:

•Under conditions where a VM I/O throughput is considerable

•In conditions where space is not being reclaimed after a period of time

Note:

Running the Off Line Coalesce tool will incur some downtime for the VM, due to the suspend/ resume operations performed.

Before running the tool, delete any snapshots and clones you no longer want; the script will reclaim as much space as possible given the remaining snapshots/clones. If you want to reclaim all space, delete all snapshots and clones.

All VM disks must be either on shared or local storage for a single host. VMs with disks in both types of storage cannot be coalesced.

Reclaiming Space Using the Off Line Coalesce Tool

Note:

Online Coalescing only applies to LVM-based SRs (LVM, LVMoISCSI, and LVMoHBA), it does not apply to EXT or NFS SRs, whose behaviour remains unchanged.

Using XenCenter, enable hidden objects (View menu -> Hidden objects). In the Resource pane, select the VM for which you want to obtain the UUID. The UUID will displayed in the General tab.

In the Resource pane, select the resource pool master host (the first host in the list). The UUID will be displayed in the General tab. If you are not using a resource pool, select the VM host.

1.Open a console on the host and run the following command:

xe host-call-plugin host-uuid=<host-UUID>\ plugin=coalesce-leaf fn=leaf-coalesce args:vm_uuid=<VM-UUID>

For example, if the VM UUID is 9bad4022-2c2d-dee6-abf5-1b6195b1dad5 and the host UUID is b8722062- de95-4d95-9baa-a5fe343898ea you would run this command:

xe host-call-plugin host-uuid=b8722062-de95-4d95-9baa-a5fe343898ea \ plugin=coalesce-leaf fn=leaf-coalesce args:vm_uuid=9bad4022-2c2d-dee6-abf5-1b6195b1dad5

58