Hi!
I planned to create with 2 identical servers: XCP-NG + HALIZARD for HA + DRDB.
I needed to use a very big, about 100GB (or sometimes 400GB) Innodb Percona Mysql database with multiple copies.
Normally we use 3 identical server + Debian + Percona Mysql cluster without any virtualization as database server, all works fine.
But with this 2 halizard HA server (where is only 1 active and 2. only DRDB sync and passive) we need to sync from that 3 node Percona cluster async the changes and we planned to use other copies of 100GB database same time for local usage. So it's like an online backup of database we want also use this server.
My idea 1: as VM, I install only 1 Percona Mysql instance (will work as single Mysql server, not as cluster), and with different databases will we use the copies of 100GB Innodb database. Disadvantage: we cannot test a working of cluster. Advantage: no 3 node Mysql data duplication overhead.
My idea 2: for 2 node cluster I will install for server1 and for server2 1-1 Percona Mysql VM, and using for storage the local SSD RAID1 storage. This plan disadvantage: only 2 node, not 3 as needed and local storage so small, so can be not enough space for full database. Advantage: got 2 copy of Mysql data.
My idea 3: adding 3 VM and we got 3 Percona Mysql node but big resource waste I think: both of CPU, RAM, IO and disk usage too, because 100GB database will use 300GB space, etc. Disadvantage: waste of resources, slow, not nice solution. Advantages: 3 copy of database, and got 3 node Mysql cluster. Also if async to external 100GB datasbase it do all times writing all of 3 VM nodes.
My idea 4: using 2 more local, slower server possible to create 3 node Percona Mysql cluster: node1 in that 2 identical server, and node2 and node3 is VM or in Debian without virtualization. Disadvantage: slower mysql cluster because of 1GB connection only and slower, older 2 other servers, more power usage. Advantage: 3 node Mysql cluster, 3 different copy of backup.
What do you think? What is your recommendation and why? Please tell me plan 5! 
Thank you my friend.