Storage is the most critical and valuable resource in a virtual environment as it serves as the persistent foundation for the virtual machines running on a host. Because storage can make or break a virtual environment, having a properly architected and well-performing storage system is paramount. Storage is typically also the most costly part of your virtual environment as well.
Because of all these factors, you need to ensure that your storage operates at peak efficiency without bottlenecks and that you do not needlessly waste space. Managing your storage resources is a constant challenge - not only do you need to ensure that they perform well, you also need to ensure you have sufficient capacity for your virtual machines.
The Biggest Virtualization Challenge: Manageing VM Snapshots
One of the biggest challenges with virtual disks lies in managing VM snapshots and thin disks. Thin disks allow for over-provisioning of storage resources as virtual disks start with a minimum of space and grow as needed as disk blocks are written to them by the guest OS. Virtual machine snapshots can be a nuisance because they are often forgotten and slowly consume space on your datastores.
Thus, snapshots and thin disks present a double threat to your storage resources as they consume growing amounts of disk space and put your datastores at risk for running out of space. Having your datastores run out of space is a situation you want to avoid at all costs as it can result in all your VMs being suspended and data corruption within the VMs.
Of all the resources that your host supplies to the virtual machines running on it, storage is the slowest resource because it relies on mechanical hard drives. Storage resources are typically not directly attached to hosts in virtual environments and instead, shared storage is commonly used to take advantage of the advanced features that virtualization provides. The path from your VM to the underlying storage device is complicated with many individual components and queues that I/O must go through. There are also many factors that can impact storage performance and cause I/O bottlenecks such as:
- Disk alignment
- Improper configuration and settings
- Excessive I/O
- Improper architecture/design
- Too many snapshots
When an I/O bottleneck occurs, it can choke the life out of your VMs and slow them to a crawl. The biggest challenge with I/O bottlenecks is detecting them and figuring out their cause so you can resolve them. The key to this is having a good tool that can monitor your storage resources and alert you when performance is degraded and show where that degradation is occurring in your storage subsystem.
Trying to rely on vCenter Server for this can be difficult because it has only basic reporting capabilities. Veeam ONE makes storage management much easier by providing full storage monitoring capabilities including disk space, I/O latency, disk issues and datastore monitoring. Veeam ONE also helps you keep an eye on over-provisioned datastores, provides utilization trend analysis and assists in optimizing VM placement on datastores.