Everyday Virtualization

Make No Assumptions About Storage Virtualization

Storage costs remain steady, but some new approaches for virtualizing storage are making it faster and more accessible.

• By Rick Vanover
• 10/01/2013

One of the greatest recent advances in virtualization actually has little to do with virtualization itself. Virtualization has caused incredible innovation around storage systems, due in part to a somewhat consistent I/O profile -- namely ESXi and Virtual Machine Disks (VMDKs). Many of the newest innovations around storage revolve around non-rotational storage blended with rotational storage being optimized for VMs.

It's a simple business formula:

• Keep costs down for the expensive stuff, such as non-rotational storage in the form of solid-state drives (SSDs), flash or memory caching.
• Keep inexpensive and large SATA disks in place for the cold parts of a data profile.
• Put the features where people need them by making VMs work better.

Do you want some bonus points as well? Then make it easy to use.

Innovation is out there. The only catch is you and I might have to change how we go about deciding on storage for VMs. It's not storage as we've known it. If VMware VMs account for the lion's share of storage consumption in your datacenter, you should take a VMware feature-specific approach to deploying storage.

1. Server-side caching with SSDs or memory before sending to the storage system
2. Storage system tiering to SSDs and slower disks
3. Tiering across large pools of existing drive arrays

One example from this first category is a new player called Infinio Systems. Infinio installs as a virtual appliance that reserves memory to serve as an accelerator for the I/O path for NFS datastores only. It will work with any NFS storage you have. So it doesn't require you to place a hard product in the datacenter.

Infinio can truly accelerate your NFS storage by reserving RAM on hosts. It provides an easy solution to a real problem. The company offered demos at VMworld 2013 and the product is currently in beta (infinio.com).

Another example is Tintri, a physical storage system that addresses storage at a VM-aware level. Tintri fits into the second category. It's a way to let VMware VMs sit on a storage system that has both traditional rotational hard drives and SSDs in the system. The Tintri VMstore will prioritize regions of the VMDKs incurring heavy I/O to be placed on the SSDs in the appliance.

That same VMDK will have "colder" regions placed on slower, lesser expensive rotational storage. The Tintri VMstore addresses spikes in VM I/O easily and adaptively. You could easily accommodate an additional 1,000 IOPS on the appliance.

In both the Infinio and Tintri examples, providing VMs running strictly on rotational storage with a large number of additional IOPS can cause detrimental performance to other VMs, if you can even achieve it at all. Inexpensive, large-capacity drives may deliver 100 IOPS, making a spike consume the throughput of up to 10 drives just from one VM.

The reality is there are many new solutions out there. Many of them are entirely new logic. Many are built for their virtual use case. Not all systems may fit into this simple trichotomy. The third option for many existing legacy arrays is to just throw SSDs into the mix.

However you provision your storage today, take a different look at what you've done. There are so many new ways to sit in the I/O path or accelerate storage traffic. I am 100 percent convinced these new approaches to storage are key to long-term success in your virtualization journey.