Design Advice: 4 Nodes cluster

[notarobot]

Hello,
I would like some advice as I m currently thinking about building a 4 nodes cluster. The machines are all Lenovo Thinkcenter M720q mini PCs.
Each nodes has 32Gb RAM, 2x500Gb SSDs and 2xRJ45 ports.
What would be the best configuration to maximise both usable disk space and high availability ?
Thanks in advance for any help !

 

[UdoB]

First: this completely depends on your goals, expectations and your personal failure tolerance. So this is just my personal 2€¢:

• even though 32GiB is not much Ram I would always choose ZFS nowadays for integrity, cheap snapshots and so on - and its replication feature would be the basis for HA; you may reduce the Ram consumption of the ARC
• do not even think "Ceph!"
• with four nodes I would definitely plan for a "Quorum Device" via an off-cluster system - this may be a simple VM or a Raspberry Pi
• I always want a reliable system. If 2x500G in a Mirror is not enough space then buy larger ones - and use "good" SSDs with PLP
• two network cards would allow to create a "front side" network for user access to VMs and a "storage/admin" network for ssh and replication traffic; make sure to tell corosync to use both of these networks

YMMV