Challenges of Using Virtual Machines As Cloud Storage

by Ariel Maislos

 Virtual server applications enable system administrators to configure a single server or pool of servers to act as numerous individual cloud storage hosts. Clients who are using cloud storage applications run off these virtual machines and won’t be privy to the difference. From the standpoint of their hardware, cloud storage solutions run from a virtual machine and those run on bare metal are identical. Whatever networking interface they use to access remote servers interprets all requests the same way. Because of this, many organizations using cloud hosting solutions have taken a second look at the advantages that come with these configurations as well as how to overcome the challenges associated with them.

Advantages of Using Virtual Machines as Cloud Servers
Perhaps the most obvious advantage of VM-based solutions is that multiple VM tenants can execute code on the same physical hardware. A single bare metal server or even a pool of servers without this technology boots a single operating system at a time. Even if there are multiple volumes with different software that are all connected to different cloud storage arrays on a physical server, you can only use a single set of system software at a time, which can be a problem if many people are trying to access different types of cloud apps from the server at the same time. The lack of isolation prevents proper implementation of a multi-user scheme.

Each VM tenant can emulate a completely separate install and every tenant can run entirely different cloud storage apps. Ultimately this ability to feature multiple tenants on the same hardware leads to higher income per each hardware unit. Since a single-tenant physical cloud server literally has only that tenant, it won’t be as efficient from a cost perspective. The overall cost of VM servers is amortized over all cloud customers.

Isolation of each VM from one another as well as the underlying system provides an additional layer of security as well as stability. If one customer executed compromised code inside of their cloud environment, then it would only have the potential to compromise that VM without infecting others. Likewise, if they were to experience any sort of file system corruption, then said corruption would only influence the virtual disk images that make up their environment.

Virtualization allows system administrators to add or remove additional VM servers on a piece of physical hardware as needed. Staff wouldn’t need to configure the underlying operating system install when it comes time to update the number of virtual servers running on a piece of hardware. This also gives clients the ability to choose which server basis they’d like to work from. Cloud storage organizations can configure several VMs running different operating systems to serve the needs of clients who have cloud applications that run on different platforms.

Aggressive memory caching policies can even speed up the rate that VMs operate, though it’s important to remember to periodically flush the buffers out. The fact that these VMs only use as much power as they need at any given time cuts down on the amount of wasted CPU processing power that tends to happen on bare metal. Legacy storage technologies aren’t an issue either, which cuts down on the risk of data loss from reliance on these technologies.

Challenges Related to Using Virtual Machines as Cloud Servers
System administrators grapple with several challenges related to VM cloud servers, but they’re quickly developing new techniques to overcome these. Virtualization, at least in theory, can waste resources if these processes depend on the same configuration settings and can exist in a single bare metal system. Those without multiple tenancies may wish to use this kind of system. However, this is becoming less relevant considering that as soon as someone wants to run more than one app at a time in a cloud environment, the lack of isolation prohibits running them properly.

Some administrators prefer to avoid using virtualization for private cloud storage solutions in relatively small organizations. They may view the additional configuration needed to get a VM cloud solution going to be unnecessary, but this all depends on the type of apps they’re running. In many cases utilization will be very low, which actually means that virtualization will allow administrators in these situations to purchase less physical server hardware.

Emulating hardware on other hardware in real time does admittedly require a sizeable amount of CPU clock speed and RAM. While isolation provides a layer of security, the so-called noisy neighbor effect on a multi-tenant server can sometimes rear its ugly head during peak load times. High loads from one tenant could consume so many physical system resources that it could slow down other cloud tenants. Isolation ultimately makes it difficult to manage load balance in these situations. Single-tenant bare metal servers don’t have this problem in theory. Server costs continue to fall, however, which means that installing stronger hardware in order to overcome this challenge is once more becoming an affordable option.

Overcoming VM Challenges
Changes in usage patterns have already made VMs take over a majority of hosting duties. Single-tenant bare metal cloud storage servers might soon give way to VMs in organizations still using the older paradigm. This will help to provide both hosts and clients the safety and performance they expect from their hosting solutions.

Ariel Maislos is the CEO of Stratoscale.

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