Virtualized Databases: Striking the Right Balance between Solid State Technologies and Spinning Disks

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is brings us to the question of uptime. How do we maintain database access when some of this superfast equipment has to be taken out of service? Again, device-independent storage virtualization software has much to offer here. Particularly those products which can keep redundant copies of the databases and their associated files on separate storage devices, despite model and brand differences. What’s written to a pool of flash memory and HDDs in one room is automatically copied to another pool of flash/HDDs. The copies can be in an adjacent room or 100 kilometers away. The software effectively provides continuous availability using the secondary copy while the other piece of hardware is down for upgrades, expansion or replacement. Same goes if the room where the storage is housed loses air conditioning, suffers a plumbing accident, or is temporarily out of commission during construction/remodeling.

The products use a combination of synchronous mirroring between like or unlike devices, along with standard multi-path I/O drivers on the hosts to transparently maintain the mirror images. They automatically fail-over and fail-back without manual intervention. Speaking of money, no special database replication licenses are required either. The same mechanisms protecting the databases also protect other virtualized and physical workloads, helping to converge and standardize business continuity practices.

And for the especially paranoid, you can keep distant replicas at disaster recovery (DR) sites as well. For this, asynchronous replication occurs over standard IP WANs.

If you follow the research from industry analysts, you’ve already been alerted to the difficulties of introducing flash memories/SSDs into an existing database environment with an active disk farm. Storage virtualization software can overcome many of these complications and dramatically shorten the transition time. For example, the richer implementations allow solid state devices to be inserted non-disruptively into the virtualized storage pools alongside the spinning disks. In the process, you simply classify them as your fastest tier, and designate the other storage devices as slower tiers. The software then transparently migrates disk blocks from the slower drives to the speedy new cards without disturbing users. You can also decommission older spinning storage with equal ease or move it to a DR site for the added safeguard.

Need for Insight

Of course, you’d like to keep an eye on what’s going on behind the scenes. Built-in instrumentation in the more comprehensive packages provides that precious insight. Real-time charts reveal fine grain metrics on I/O response and relative capacity consumption. They also provide historical perspectives to help you understand how the system as a whole responds when additional demands are placed on it, and anticipate when peak periods of activity are most likely to occur. Heat maps display the relative distribution of blocks between flash, SSDs and other storage media, including cloud-based archives.

What can you take away from this? For one, solid state technologies offer an attractive way to accelerate the speed of your critical database workloads. No surprise there. Used in moderation to complement fast spinning disks and high-capacity, bulk storage already in place, SSDs help you strike a nice balance between excellent response time and responsible spending. To establish and maintain that equilibrium in virtualized scenarios, you should accompany the new hardware with storage virtualization software – the device-independent type. This gives you the optimal means to assimilate flash/SSDs into a high-performance, well-tuned, continuously available environment. In this way, you can please the financial overseers as well as the database subscribers, not to mention all responsible for its caring and feeding - you included.

About the author:

Augie Gonzalez is director of product marketing for DataCore Software and has more than 25 years of experience developing, marketing and managing advanced IT products.  Before joining DataCore, he led the Citrix team that introduced simple, secure, remote access solutions for SMBs. Prior to Citrix, Gonzalez headed Sun Microsystems Storage Division’s Disaster Recovery Group. He’s held marketing / product planning roles at Encore Computers and Gould Computer Systems, specializing in high-end platforms for vehicle simulation and data acquisition.

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