Server SANs And Healthy Paranoia update from March 2014

Server SANs such as VMware VSAN are designed for virtualization administrators, but are these new storage buyers paranoid enough to be entrusted with storage management?

Howard Marks

March 18, 2014

3 Min Read
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Chuck Hollis, chief strategist for VMware's storage and application services business unit, has blogged that the now generally available VMware Virtual SAN (VSAN) is designed to appeal to a new class of storage buyers. The people who are going to buy server SANs like VSAN aren’t established storage teams, but virtualization administrators. I wonder whether some of these virtualization admins are paranoid enough to be trusted with storage at scale.

Storage vendors from EMC to Tegile have sold storage to -- or in the case of SMBs, through -- experienced storage people. VSAN, and server SANs in general, aren’t designed to make steely-eyed storage guys turn away from dedicated storage for the promised land of software-defined storage. Instead, they’re designed to give the virtualization admin an alternative to dealing with the storage guys altogether.

I fully understand that many corporate storage teams can be inflexible, raising the cost of storage for use cases such as test, development and tier-two applications to unreasonable levels. After all, storage guys are the most conservative people in most datacenters and they do sometimes go too far.

It is, however, important to remember why the storage guy is so paranoid. While server and network admins all have their own “oh crud” moments, those rarely rise to the level where they're worried not only that they'll lose your job, but that they've screwed up badly enough to put the company out of business. Once you’ve reverted to the working version of the router firmware, the router works just as well as it did before you flubbed the firmware upgrade.

But when you accidentally swap out the wrong drive on a disk array, wiping out several terabytes of data, you have to spend many hours restoring data from backups. And even if that goes flawlessly, you’ve lost anything stored since the last good backup. I for one don’t really trust anyone with my storage unless they have a visceral fear of anything that might cause data loss.

[Find out the real reason disk drives haven't gotten faster than 15K RPM in "The Myth Of The Supersonic Disk Drive."]

Since today's hypervisors allow us to move workloads between hosts, or storage systems, with only a minimal impact on those VMs' performance, virtualization admins routinely vMotion all the virtual machines off a host for hardware maintenance without scheduling downtime or following complex change control procedures. In contrast, even though manufacturers promise non-disruptive controller firmware updates, storage admins always schedule downtime and plan the process of reverting back to the previous version before updating their systems

When we converge storage into the virtualization environment, admins are going to have to realize that when they take a host offline, it will reduce both the performance and resilience of their storage as well. I’m afraid we’ll start seeing horror stories of an admin that sets up two-way replication in VSAN, takes a host offline for maintenance, and then loses data when a single disk fails.

If the shift to server SANs starts with test, development and tier-two applications, the virtualization guys will have enough close calls to realize that when it comes to storage, some paranoia is a good thing. When former Intel CEO Andy Grove famously said “only the paranoid survive,” he of course was talking about business, but I think the line applies even better to storage.

[Howard Marks will be talking about flash and software-defined storage at Interop in a half-day workshop "Deploying SSDs In the Data Center" and a pair of sessions "Using Flash On The Server Side""Using Flash on the Server Side" and "Software-Defined Storage: Reality or BS?"]

About the Author(s)

Howard Marks

Network Computing Blogger

Howard Marks</strong>&nbsp;is founder and chief scientist at Deepstorage LLC, a storage consultancy and independent test lab based in Santa Fe, N.M. and concentrating on storage and data center networking. In more than 25 years of consulting, Marks has designed and implemented storage systems, networks, management systems and Internet strategies at organizations including American Express, J.P. Morgan, Borden Foods, U.S. Tobacco, BBDO Worldwide, Foxwoods Resort Casino and the State University of New York at Purchase. The testing at DeepStorage Labs is informed by that real world experience.</p><p>He has been a frequent contributor to <em>Network Computing</em>&nbsp;and&nbsp;<em>InformationWeek</em>&nbsp;since 1999 and a speaker at industry conferences including Comnet, PC Expo, Interop and Microsoft's TechEd since 1990. He is the author of&nbsp;<em>Networking Windows</em>&nbsp;and co-author of&nbsp;<em>Windows NT Unleashed</em>&nbsp;(Sams).</p><p>He is co-host, with Ray Lucchesi of the monthly Greybeards on Storage podcast where the voices of experience discuss the latest issues in the storage world with industry leaders.&nbsp; You can find the podcast at: http://www.deepstorage.net/NEW/GBoS

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