Libro sobre Proxmox maestria
Shared Storages with Proxmox
Thin provisioning is when the virtual disk image file does not preallocate all the blocks, thus keeping the size of the image file to only what we want. As more data is stored in the virtual machine, the thin provisioned image file grows till it reaches the maximum size allocated. Thick provisioning, on the other hand, is when the virtual disk image file preallocates all the blocks, thus creating an image file which is exactly of the size set prior to creating the virtual disk image file.
The .qcow2 format also has very high I/O overhead due to its additional software layer. Thus, it is a bad choice of image format for a VM such as a database server. Any data being read or written into the image format goes through the qcow2 software layer, which increases the I/O making it slower. A backup created from a qcow2 image can only be restored to an NFS or local directory.
When budget is the main concern and storage space is very limited, qcow2 is an excellent choice. This image type supports KVM live snapshots to preserve states of virtual machines.
The raw image type is also a very stable and matured VM image format. Its primary strength lies in performance. There is no additional software layer for data to go through. VM has direct pass-through access to the raw file, which makes it much faster. Also, there is no software component attached to it, so it is much less problem prone. The raw format can only create a fixed-size or thick-provisioned VM image file. For example, an Ubuntu VM created with 50 GB storage space will have a 50 GB image file. This helps an administrator to know exactly how much storage is in use, so there is no chance of an uncontrolled out-of-storage situation.
The raw type is the preferred file format for all Proxmox VMs. A raw image format VM can be restored to just about any storage type. In a virtual environment, additional virtual disk image files can be added to a virtual machine at any time. So, it is not necessary to initially allocate a larger size. raw virtual disk image file with possible future growth in mind. The VM can start with a smaller raw image file and add more disk images as needed. For example, a VM with 50 GB data starts with an 80 GB . raw image file. It then adds more virtual disk images at a 50 GB increment as need arises. Proxmox allows quite a few additional virtual drives to be added to a VM. The following is a table of the maximum number of allowed disk device per VM by Proxmox: