vSohill
Expert
Expert

System vMotion

Jump to solution

Hi,

How can I reduce VM vMotion that is initiated by the system (vCenter)? What is the cause for vCenter to generate  vMotion even the compute and net usage is less than 20% in the cluster nodes  ?

DRS automation level set to the default level

0 Kudos
1 Solution

Accepted Solutions
a_p_
Leadership
Leadership

DRS takes VM resource reservation into account, which may cause DRS to trigger migrations. This not necessarily the root cause in this case, but worth checking whether the reservations are required, and removing them if possible to see whether this makes a difference.

see DRS Cluster Management with Reservation and Shares

André

View solution in original post

0 Kudos
6 Replies
SupreetK
Commander
Commander

Can you share a couple of screenshots depicting the vMotion tasks in question and the load on the ESXi hosts from the cluster view? Also, set the migration threshold to level-2 (center of Conservative and Aggressive) from vSphere DRS settings.

Cheers,

Supreet

0 Kudos
vSohill
Expert
Expert

Thank you SuppertK. I will not be able to share a screenshots, the customer has kind of restrection of access and gathering info about their infra.

The migration threshold is set to level-3 I will try to tuned it level-2.

DRS will try to grant the amount of compute to VM needs not to balance the cluster am I assuming right ?

0 Kudos
SupreetK
Commander
Commander

Setting it to level-2 will definitely help. Working of DRS depends on the configuration of your environment. More details in the below links -

https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vsphere6-drs-perf.pdf

DRS Deepdive - Yellow Bricks

Cheers,

Supreet

0 Kudos
a_p_
Leadership
Leadership

With the default settings, DRS should only generate recommendations, i.e. migrate VMs in case of contention, or to comply with DRS rules.

Depending on the vSphere version, there are different settings which could cause migrations, like even distribution of VMs across hosts, predictive DRS, ...

Other thoughts:

When do these migrations happen? Are there any VMs which cause temporary high load (CPU, and/or memory)?

Do any of the VMs have reservations?

Are the VMs which are migrated always the same, or does it happen for random VMs?

André

0 Kudos
vSohill
Expert
Expert

Thank you Andre'

Yes there is reservations for some VMs. How reservations affect on vmotion that initiated by the system?

0 Kudos
a_p_
Leadership
Leadership

DRS takes VM resource reservation into account, which may cause DRS to trigger migrations. This not necessarily the root cause in this case, but worth checking whether the reservations are required, and removing them if possible to see whether this makes a difference.

see DRS Cluster Management with Reservation and Shares

André

View solution in original post

0 Kudos