Who’s the real SDS?
As discussed in the first section, I believe that the proprietary products strategy and the monopoly profit model is the reason for traditional storage products becoming obsolete in the foreseeable future. If we assume that traditional storage vendors changed their strategy, such that storage is no longer a proprietary system, but rather an open system, then what is the form of their core technology? Evidently, the answer is software.
Hardware: it’s all the same
Actually with regards to hardware, all vendors are essentially the same, the hardware of storage systems is essentially two or more so called “controllers”, which are servers with special operating storage management software embedded, and a load of hard drives. The essential difference between different storage systems is the bundled ‘storage management software’, not the hardware. In fact, all current mainstream storage systems already utilises the standard x86 hardware framework, owing to this, a user only needs to install the storage software onto a server, or even a virtual server, then it can realise almost all its storage functions, for example, creating and provisioning storage resource, protecting the data by mirroring, snapshots, remote replication, directly turning this server with its connected storage resources (be it internal hard drives, JBODs or storage arrays) into a storage system. This is the essence of software defined storage (SDS).
Software: Two Types of SDS
Every vendor and research firm has different classification methods for SDS. Some in accordance with deployment practices divide into software, hardware and appliances; but these categories do not have much guiding significance for actual deployments. For example, hyper-converged infrastructure is deployed as an appliance or hardware, but the core technology is the Server SAN software; Server SAN and storage virtualisation are both available as software but they serve completely different segments of the market. I believe that the commercial SDS solutions can be categorised into two types:
These two kinds of solutions focus on two different levels of problems, use different methods to serve different markets and different scenarios. In fact, there is almost no competition between the two groups, so it is necessary to categorise prior to conducting analysis.
Server SAN steals spotlight, but it’s not a competition
The first group, system level SDS, especially Server SAN is the current point of interest within the industry. Many people are discussing whether Server SAN and hyper-convergence will replace traditional storage arrays. The leaders of which, such as Nutanix and VMware VSAN are currently celebrities under the spotlight, to the point that many people have forgotten about the existence of the second kind of data centre level SDS solution. However, I believe that the value of the second group of SDS has been heavily underestimated by the end users and storage vendors. They should all rediscover the value of this kind of SDS.
The first group of solution transform servers into storage systems to rip and replace legacy storage arrays. There have already been countless articles describing the advantages; these points do not need reiterating. But as a sceptic, I have to raise my doubts, because in the last three decades, there have been so many new storage technologies promising solutions that are more cost-effective and simpler to manage. However, the eventual practical consequence is exactly the opposite because they have been creating more and more management silos which makes the infrastructure even more expensive and complicated. Server SAN is unlikely to rip and replace all legacy storage, again we will see this sort of pattern emerge.
The second group of SDS has storage virtualisation at its core, and achieves SDS on the data centre level. These solutions add a new virtualisation layer upon current storage, and connect to the various storage systems to create a composite virtualised storage resource pool, and from this provide a variety of storage services, such as snapshots, disaster recovery, deduplication and CDP. This approach unlocks storage capabilities of existing investment and the storage system hardware; where end users can easily realise data flow, migration and management across heterogeneous storage systems.
Obviously this group of SDS integrates, instead of replaces the traditional storage array. For those enterprises who have already purchased many traditional storage arrays, this is evidently a more reasonable solution rather than to rip and replace. In addition, this group of SDS and the first group do not compete; in fact, the first group of SDS can also serve as a storage resource for integration. SDS virtualisation can bridge the legacy system into the new model data centres during the transformation, helping users smoothly enter the era of software defined data centre (SDDC). And, just because of this, I believe that the first glimmer of hope for traditional storage is in SDS virtualisation.
Bringing the best of both worlds
In SDS virtualisation management, traditional storage arrays are utilised and consolidated into a unified resource pool, the users will keep using them so the investment is not wasted, and this solution also avoids high risk tasks such as data migration. In addition, it unlocks the original vendor lock-in. Data could freely flow between different systems, storage expansions and disaster recovery would no longer necessarily use the same product, therefore, the user would regain their bargaining power with the vendor. However, unlike Server SAN, SDS virtualisation does not provide low level storage management such as hard drive management, and because of this, traditional storage arrays would still have its own value. SDS virtualisation platforms can eliminate the user’s fear of purchasing storage - so it is the ‘saviour’ of the traditional storage industry. For the end users, it is the tool to cut costs when purchasing storage systems because they regain the bargain power.
There are some challenges faced by this group of SDS:
We have the solution
FalconStor Software’s FreeStor is the representative for these solutions. During the past 15 years of technological progress and evolution, FreeStor has become the leader of this kind of products. FreeStor, including its previous versions, has already been installed on 50,000 servers worldwide and has not a single instance of data destruction or loss, and it has virtually no functional impact on related storage arrays. In comparison, virtualisation solutions by storage system vendors often involve moving storage arrays of other companies to its own systems, leading to many compatibility issues. Many users have come across problems such as performance impact and functionality loss during deployment. FreeStor’s cluster infrastructure, along with all-flash array vendors’ close co-operation verifies its high-performance, and ensures hardware compatibility. In contrast with the storage virtualisation solution of storage array suppliers, as a third-party software provider, FalconStor Software can connect with almost all storage products and will not become a new manufacturer lock-in.
Server SAN vs SDS Virtualisation
If we further compare the two kinds of SDS, we will make some new interesting discoveries.
Server SAN’s mission is to rip and replace traditional storage arrays. Server SAN and hyper-converged solutions are the mortal enemy of traditional storage arrays. In Server SAN’s ideal world, there is no place for traditional storage arrays. SDS virtualisation is to be integrated with all storage, no matter whether traditional storage arrays or hyper-converged ones. For any users, to rip and replace existing systems is a matter which requires careful consideration, that’s why many Server SAN projects stall at the experimental stage.
As the usage of many Server SANs is limited by Hypervisor itself, scenarios such as cross virtual environment and physical environment, cross multiple different virtual environments, and usage across geographic locations can all be hard to implement, becoming much more complicated. Solutions provided by virtualisation providers, such as VMware VSAN, cannot manage across other virtualisation environments. In contrast, the deployment of SDS virtualisation can cross any hypervisors, physical and virtual environments.
The main attraction of the Server SAN solution is that it lowers costs. The design philosophy of Server SAN is to assume that the cost of storage in the server itself is very low, so it equips with a crude method to achieve fault tolerance, such as creating multiple copies. In most cases, the storage utilisation rate is under 30%. In contrast, SDS virtualisation usually uses RAID mechanisms to protect data, so storage utilisation rate is between 50%-80%. Evidently, SDS virtualisation is more efficient. But the storage vendors on the actual market often sell several times more than the actual hard drive cost, that’s why it is more expensive than hyper-converged solutions. This signifies that this cost comparison only exists owing to the huge profit model of tradition storage vendors. If traditional vendors adopt a new micro-profit model, storage costs would significantly drop, so, they have an opportunity to secure a certain amount of profit while breaking the price advantages posed by Server SAN and hyper-convergence.
For enterprise users, it is necessary to provide comprehensive data protection services on storage infrastructure. Backup, mirroring and replication are all vital. These functions have long been standard features on storage arrays, SDS virtualisation solutions provide equal or even more advanced data protection features, such as FalconStor CDP which has long been a star product in the field of disaster-recovery. In contrast, most of Server SAN solutions are yet far from maturity in terms of data protection, and it need a long period for verification testing at the very least.
Because of this, as described above, the ideal usage environment of Server SAN should be for non-critical new businesses with no need for advanced data protection. In addition, these businesses must have already virtualised. In contrast, SDS virtualisation is the comprehensive integration of existing storage at the data centre level, no matter virtualisation deployment. For new storage at new businesses, Server SAN can be deployed fairly easily; while SDS virtualisation can be more considered for compatibility with current traditional storage.
It’s a lot of information to take in, but ultimately, it boils down to 3 main points:
The basis of the hardware is the same, despite how vendors market them. It’s the software that keep the competitions apart
Both are implemented differently and the way they work are very different. You can’t really compare them side by side.
Despite saying that you can’t compare them – there are advantages and disadvantages to each option. For enterprise, SDS virtualisation is the clear winner in the long term implementation, despite ServerSAN still being the popular choice.
Finally, traditional storage, especially high-end storage systems, at this point in time still faces a dilemma which cannot be avoided. What is it? Let’s find out in the next note.