Microsoft

vMotion Limits on Simultaneous Migrations

With vSphere 6.x VMware enhanced vmotion features which we discussed on the post and it really help full in virtual Infrastructure . But vCenter Server places limits on the number of simultaneous migration and provisioning. This is occurring on operations on each host, network, and datastore.

Operations like migration with vMotion or cloning a virtual machine, is assigned a resource cost. Each host, datastore, or network resource, has a maximum cost that it can support at any one time. Any new migration or provisioning operation that causes a resource to exceed its maximum cost does not proceed immediately, but it will be queued until other operations complete and release resources. once the resources limits must satisfy then only the operation associated will be proceed.

vMotion without shared storage, migrating virtual machines to a different host and datastore simultaneously, is a combination of vMotion and Storage vMotion. This migration inherits the network, host, and datastore costs associated with those operations. vMotion without shared storage is equivalent to a Storage vMotion with a network cost of 1.

Follow below details to understand the limitation

Network Limits

Network limits apply only to migrations with vMotion. Network limits depend on the version of ESXi and the network type. All migrations with vMotion have a network resource cost of 1.

Network Limits for Migration with vMotion
Operation	ESXi Version	Network Type	Maximum Cost
vMotion	5.0, 5.1, 5.5, 6.0	1GigE	4
vMotion	5.0, 5.1, 5.5, 6.0	10GigE	8

Datastore Limits

Datastore limits apply to migrations with vMotion and with Storage vMotion. A migration with vMotion has a resource cost of 1 against the shared virtual machine’s datastore. A migration with Storage vMotion has a resource cost of 1 against the source datastore and 1 against the destination datastore.

Datastore Limits and Resource Costs for vMotion and Storage vMotion
Operation	ESXi Version	Maximum Cost Per Datastore	Datastore Resource Cost
vMotion	5.0, 5.1, 5.5, 6.0	128	1
Storage vMotion	5.0, 5.1, 5.5, 6.0	128	16

Host Limits

Host limits apply to migrations with vMotion, Storage vMotion, and other provisioning operations such as cloning, deployment, and cold migration. All hosts have a maximum cost per host of 8. For example, on an ESXi 5.0 host, you can perform 2 Storage vMotion operations, or 1 Storage vMotion and 4 vMotion operations.

Host Migration Limits and Resource Costs for vMotion, Storage vMotion, and Provisioning Operations
Operation	ESXi Version	Derived Limit Per Host	Host Resource Cost
vMotion	5.0, 5.1, 5.5, 6.0	8	1
Storage vMotion	5.0, 5.1, 5.5, 6.0	2	4
vMotion Without Shared Storage	5.1, 5.5, 6.0	2	4
Other provisioning operations	5.0, 5.1, 5.5, 6.0	8	1