Kool-Aid. It’s great stuff. When you believe it hard enough, it enables you to do amazing things. Doubt is not a problem. You simply state the company position as truth, uncritically. This gives you tremendous power in your customer presentations. Like I said, if you believe it hard enough.
Funny thing though. After a while Kool-Aid begins to lose its punch. You have to redefine the message. Reformulate the Kool-Aid you will. Otherwise, nagging doubt begins to erode your confidence. You get that haunted look as you deliver the message. Like what you are saying may not be exactly true. This detracts from the appeal of the Kool-Aid, especially as the customer begins to perceive that you may not be shooting straight.
Don’t get me wrong. All companies have Kool-Aid. I would readily admit that EMC has Kool-Aid too. When I first showed up at EMC, I had the following conversation multiple times with many different individuals:
Me: “What do you think about NAS storage for Oracle databases?”
EMC person: “NAS is great for storing small, non-mission critical Oracle databases with low I/O requirements.”
That’s Kool-Aid. Much of what I have been doing at EMC since I showed up here has been combating this particular brand of Kool-Aid. Because my entire professional life for the past 10 years has largely been about Oracle on NAS storage. Because I can run out of fingers and toes on my entire body counting Fortune 1000 companies which I have visited personally that have multiple PBs of NAS-mounted Oracle databases which they use in mission critical settings, and hit with heavy I/O loads. Many of these databases are multiple TBs in size as well. Including, most importantly, Oracle Corporation.
So, yes, NAS is perfectly appropriate for storing Oracle databases of all kinds and sizes with all sorts of I/O requirements. Including databases which the customer absolutely has to have running always. Which Oracle Corporation itself has proven in spades.
All of which is to say that I war against Kool-Aid. In all forms, and at all times. Whether from my existing employer or not. Despite its insidious power. In fact, because of it. The truth must be embraced, and Kool-Aid must be rejected, always.
Getting back to NetApp, the snapshot-for-Oracle-hot-backup form of Kool-Aid began to lose effectiveness in the last couple of years of my tenure there (basically 2004 and 2005), and there was a lot of soul searching for another message. The message which emerged centered on the notion of writable snapshots in the form of FlexClones which were introduced in ONTAP 7. FlexClones work like this:
Similar to my last post, this graphic represents the state of a WAFL file system before and after a set of updates. The blocks belong to three files, color-coded pink, buff, and green. Compared to my last post, another set of “after” images of the blocks have been created. These are the blocks created by FlexClone write activity. This has one major side effect. The space held by the snapshot (referred to as snapshot overhead) increases as write activity within the FlexClone file system occurs. Previously, the blocks held by the snapshot (the light-colored blocks) were only the before images of blocks which were overwritten by the production file system. Now another write thread has been created, which will cause more before images of blocks to be held by the snapshot. This will increase the snapshot storage overhead. I will discuss snapshot storage overhead in detail in a future post.
FlexClones were introduced with great fanfare in 2005 and the claim was widely made by many folks at NetApp (myself included), that they were “completely unique to the industry”. Without question, that’s the purest form of Kool-Aid.
Recall the conversation I told you about in my last post with a major telecom customer in the UK. Here is the rest of that conversation:
Me: “NetApp is the only storage company to have writable snapshots! FlexClones are completely unique to the industry!”
Customer: “What are you talking about? CLARiiON SnapView snapshots are writable and always have been. So are Symmetrix Timefinder Snap snapshots. EMC has had this functionality for years.”
I must admit that I feel fairly stupid about this now. In my defense, there was a widespread view within NetApp that undue familiarity with EMC as a competitor was unhealthy. I lived in a state of shocking ignorance concerning the capabilities of EMC storage arrays and software. This ignorance was completely fine as far as my employer was concerned.
The functionality of EMC writable snapshots is somewhat similar to NetApp’s FlexClones. The following graphic points out how they work:
In EMC’s case, the after images of blocks modified in the snapshot are simply written to the RLP LUNs. This eliminates the additional snapshot overhead, at the cost of not maintaining the original version of that data. Again, a weighing exercise. With EMC snapshots, if you want to keep the original version, you must not overwrite it.
Kool-Aid. Watch out for it. It will suck you in. In future posts, I will continue to point out the areas in which the storage-for-database messaging has been less than totally honest. Stay tuned.