Limiting the Number of Donor Nodes

[igre...@labattfood.com]

Is there a way to limit the number of simultaneous donor/ssts going on in a cluster?

We have the following case that happens to us.  Each datacenter has 2 nodes in the following states:

Datacenter A - Synced, Synced

Datacenter B - Synced, Synced

Datacenter C - Synced, Synced

Then we will have a power outage or some other network issue in one of the datacenters resulting in the following:

Datacenter A - Synced, Synced

Datacenter B - Synced, Synced

Datacenter C - Offline, Offline

When datacenter C rejoins the cluster both nodes require a SST resulting in the following state:

Datacenter A - Synced, Synced

Datacenter B - Donor, Donor

Datacenter C - Receiving SST, Receiving SST

Thus, our cluster with 6 nodes drops all the way down to two functional nodes which are not enough to handle the query volume.  It also causes a network bottleneck as Datacenter's B & C now are using a lot of bandwidth to make the transfer.  Is it possible to limit the cluster to only have 1 SST going on at any particular time?  It's better for the nodes to delay coming back up (one at a time) rather than try to SST both at the same time.

We have optimized other settings, such as the size of the galera gcache, etc.

Thank you!