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February 01, 2012

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mahargk

Whether the hardware is LSI or Fusion, how is this materially different from FB's flashcache work (for the generic case, or 11G-R2 for the app-centric case) that's been available for some time now, without paying "enterprise storage" margins? Other than inconclusive summations with condesention and emoticons, where's the value and differentiation?

Chuck Hollis

Rather than repeat my entire post as an answer, I'd encourage you to read the material here.

Thanks!

Roy DCruz

Chuck, sure thing - a PCI flash card sitting on a bus directly across from a processor will allow for faster completion of IO via a serial link (FC, GE, whatever other link) ... if there exists applications that issue IOs that can saturate serial links. In the past, such applications did not exist (just because of concepts such as READ-READ and READ-WRITE barriers).

16 Gbps serial links can handle IO rates of 2 Million IOPS (at 1000 byte IO size which is a rate large IO size for OLTP). H'mm, I cannot think of any "application" that can spew out 2 Million IOPs. And if this data point is valid, then the serial link argument being the choke point is invalid!

Flash cards sitting on a PCI bus is DAS architecture. And there were a lot of problems with DAS architecture. I realize that EMC's VFCache spin is not exactly DAS (like FusionIO) but by way of the Flash card, you have introduced one more moving part and one more management point.

One of the arguments of array based SAN attached storage is that it is centralized! You have one management point and you can deliver a rich set of storage services from this centralized management point.

Another argument I heard in the past was that one array port had more than enough performance capacity so as to be able to provision between 8 and 16 hosts (initiators) to access LUNs via 1 array port (fan in). Are we now saying that array ports can be saturated by ONE server?

Whatever happened to the argument that battery backed RAM caches in Storage Array's are capable of delivering the highest of performance needed by any server?

The newer pitch that servers are able to generate IO at much faster rates than an array port are capable of servicing is a contradiction of previous arguments.

Any clarification regarding these seemingly contradictory arguments will help reconcile the confusion.

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Chuck Hollis


  • Chuck Hollis
    Chief Strategist, VMware Storage and Availability Business Unit
    @chuckhollis

    Chuck works for VMware, and is deeply embroiled in all things software-defined storage these days.

    Previously, he was with EMC for 18 years, most of them great.

    He enjoys speaking to customer and industry audiences about a variety of technology topics, and -- of course -- enjoys blogging.

    Chuck lives in Holliston, MA with his wife, three kids and four dogs when he's not traveling. In his spare time, Chuck is working on his second career as an aging rock musician.

    Warning: do not buy him a drink when there is a piano nearby.
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