Dynamic Provisioned & Dynamically Tiered Storage - Explained

Having looked around on internet for good references to these topics I found varied descriptions, so I've decided to create my own definition using a diagram (I learn better with Pictures).

Picture Reference, courtesy of myself:

Goodbye VMA for storage integration….Hello VASA API

Not long ago VMware announced that the VMA (Virtual Management Appliance) that is currently used as a conduit between the array and virtual centre would be wound up and replaced by a new storage API that will provide even tighter integration with storage arrays.

The API is called VASA – Vmware Aware Storage API

With this new level of integration VMware are touting that operations such as DRS (Dynamic Resource Scheduling) could be applicable for storage, where I/O intensive VM’s will be moved to higher performance LUNs/Datastores by way of array integration.

This causes a “catch 22” though as tiered storage environments will already being taking care of this at this back-end. However if your subsystem doesn’t support tiering, this API will be great for dynamic movement high I/O VM’s.

How to choose a storage vendor?

Recently I have noticed a number of discussions taking place on sites such as Linkedin under the “Storage Experts” and “Storage Processionals” section that ask for references on which vendor is best.

Reading the comments it is evident that there are some “die hard” vendor supporters out there that would rather sell their first born than stray to a different vendor.

With 7 years experience in the IT industry, I have seen my fair share of vendor "pre-sale" presentations and I must admit that it's easy to get sucked in by the impressive  powerpoint slides and marketing speak - each vendor will no doubt hold benefits for you or your organisation, but first you need to first ask a few key questions so the best possible decision can be made:

• Scalability - Current storage and projected storage requirements for up to 3 years
• Types of hosts/applications accessing the disk along with typical I/O requirements from each vendors host/application (read vs write, random or synchronous & spikes or consistent)
• Budget Range – remember that a SAN or NAS doesn’t just mean the subsystem, you will need:

o   Cabling (Fibre or Copper)

o   Switching (Fibre, Ethernet or Converged (FCoE))

o   Hosts Bus Adapters (HBA’s) for hosts

o   Multipathing Software for link redundancy
o   Management tools

• Existing infrastructure for possible leveraging – e.g. spare switches for an ISCSI solution
• The need for file level storage (NAS) or block storage (SAN) or both
• Return on investment (ROI) time
• Subsequent years of maintenance support
• Vendor presence in your area – are there others customer sites you can reference
• SLA's on support services
• VAAI Support (VMware API’s for Array Integration) – This allows performance gains by offloading I/O intensive tasks to the subsystem and is becoming increasingly important amoungst large and I/O intensive VMware environments
• Dynamic pooling and tiering capabilities – this can dramatically reduce your spindle count when going for performance

With these key items covered you should be well positioned for your vendor decision.

On a side note I would recommend not just to consider the “big” vendors as there are a number of promising storage start-ups appearing in the Market such as Tintri http://www.tintri.com/. These companies are beginning to gain momentum and can often provide a great solution for much less money – that is until they are consumed by one of the “big” vendors. 

Also, if you are really strapped for cash and are not too fussed on support services, there is always the open-source path:

• Free NAS http://www.freenas.org/
• Open Filer http://www.openfiler.com/

    This software installs itself as an operating system that is compatible on most x86 systems and literally turns a server into a subsystem where you can define ISCSI or FC targets on the local storage. I would suggest at minimum though that you have a hardware maintenance agreement on the server & sturdy RAID controllers for the local storage.

Also, as a side reference check out the magic quadrant from Gartner below, which highlights the vendors currently excelling in the storage industry:

Finally...Good Luck!