Wednesday, July 01, 2015

A Reply to Chris M. Evans' "The NetApp Conundrum"

Storage blogger Chris M. Evans wrote a recent post on LinkedIn entitled "The NetApp Conundrum".

As a NetApp employee, and long-time member of the IT vendor industry, I have provided the following response.

I am having trouble resolving two points you made Chris. One is Data ONTAP is old (23 years, to be exact), and storage architectures only last 20 odd years. The second is clustered Data ONTAP is not Data ONTAP (the 23 year old one), but a new and different product created by merging some of Spinnaker's technology (acquired in 2003), with some of NetApp's technology in 2009. By my math, that makes clustered Data ONTAP six years old, and by your own calculation, it has 14 years of longevity left.

A few other points:

It is impressive HDS VSP's SVOS can run on a laptop. I can run a four-node clustered Data ONTAP cluster on my laptop.

The debate over the HA-Pair construct vs. a multi-node HA construct is an engineering and design debate, based on customer requirements, performance, time to market, predictable failure characteristics, and trade-offs--not ideology or perceived elegance. I would note VMAX engines are failover pairs for the same reason we use failover pairs in clustered Data ONTAP. It is also worth noting EMC changed the cache mirroring approach in Isilon with its Endurant Cache to a logical cache pair construct to maximize performance. Similar to clustered Data ONTAP, EMC XtremIO uses a cluster constructed of failover pairs, and Pure Storage use a failover pair scale up architecture similar to NetApp 7-Mode or EMC VNX.

True scale-out, distributed storage is interesting, but it presents challenges in developing fast, reliable, predictable failover. It is also very difficult to implement highly efficient data protection schemes, such as parity, double/triple-parity, and erasure coding in such an architecture. There is a reason Hadoop clusters, VSAN clusters, and Nutanix clusters use mirroring and triple mirroring for data protection. Nutanix's just announced EC is only for cold data.

What is happening today is almost all of the new all-flash array start-ups (XtremIO, Pure, Kaminario, Whiptail/Cisco, and Nimbus Data), and hybrid array start-ups (Nimble, Tintri, and Tegile), use log-structured filesystems, non-volatile memory and write coalescing, write to free-space, and parity RAID algorithms as the basic underlying technologies for their arrays. These concepts are more than 20 years old. NetApp built WAFL and Data ONTAP on these concepts more than 20 years ago because they worked. And they still work today, especially for NAND flash media. That is why NetApp continues to improve and develop Data ONTAP. Because the alternative to Data ONTAP looks a awful lot like Data ONTAP. Don't take my word for it--just look at the recent hybrid and all-flash storage players out there.

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