Libro sobre Proxmox maestria
Shared Storages with Proxmox
Shared storage is not absolutely necessary in a Proxmox cluster environment, but without a doubt it makes storage management a walk in the park. In a small business with an extremely limited budget and IT staff, a local storage system will suffice. But when data grows beyond several terabytes and keeps growing exponentially every month due to virtual machine backups, shared storage starts to make a whole lot of sense. In most enterprise virtual environments with critical data, shared storage is the only logical choice due to the benefits it brings to the whole cluster operation. The following are considered benefits of using shared storage:
This is probably one of the important sought after reasons to go for shared storage system. Live migration is when a virtual machine can be moved to a different node without shutting it down first. Offline migration is when the virtual machine is powered off prior migration. Proxmox nodes need updates and patches from time to time. Some updates require immediate reboot while some require none at all. The primary function of Proxmox nodes in a cluster is to run virtual machines. When a node needs to be rebooted, all the running VMs must be stopped or migrated to other nodes. Then, migrate them back to the original node after the reboot cycle is complete. In Proxmox, a powered-on VM cannot be migrated using live migration without powering it down first if the VM is on a local disk of the node in question. The other drawback of local storage is that if a total Proxmox node failure occurs for any reason, all the VMs stored in that node will be completely unavailable until the node is fixed or replaced. This is because VMs cannot be accessed to be moved to a different node until the issue node is powered up.
In most cases, shutting down all VMs just to reboot the host node is not an option. This causes too much downtime depending on the number of VMs the node handles. In order to migrate locally stored VMs, they must be stopped and migration should be initiated from the Proxmox GUI. Migration from local storage to another local storage takes a long time depending on the size of the VM, since Proxmox moves an entire image file using rsync to relocate the VM to another node. Let us take a look at the following diagram of a cluster with 40 locally stored virtual machines with 10 on each of the four Proxmox nodes: