[feature request] VDI affinity for SR

[TristisOris]

Prioritise to choose VDI SR depend on storage class.

We have all-flash SR and HDD SR. High load and important VMs should run on flash storage, others on HDD.
At first time i can move all VDIs manually, but after any migration (especially batch migration) the default SR would be chosen.

Each pool have own dedicated physical SR: pool1 - hdd1, ssd1. pool2 - hdd2, ssd2, .. etc.
So when i (or load balancer, disaster recovery, etc) migrate any VM with ssd tag from pool1-ssd1 to pool2 - it automatically move VDI to ssd2 SR.

discusion https://xcp-ng.org/forum/topic/8252/tag-based-selection-for-multiple-vdi-storages

[MrGrymReaper]

This really could also be able to provide support for choosing VDI SR depending on not just storage class, but also other criteria.

[robhoes]

The API for cross-pool storage migration, which is VM.migrate_send has an argument to map each VDI of the VM to an SR on the target pool. So a client, such as XenCenter or XenOrchestra, should be able to offer this choice to you.