Tag Archives: mirror

Host based mirroring kills your storage network!!

System administrators are very inventive and lazy. I know, I used to be one of them. 🙂 Everything that can be done to make ones life easier is about to be scripted, configured, designed etc.  If you are responsible for an overall environment from Apps to servers to networks and storage you can make very informed decisions on how you want to set up each different aspect of your environment. The last time I had this opportunity was back in 1995. Since then I have not come across an environment where a single person/team was responsible for each technology aspect of the infrastructure. As environments grow these teams grow as well. Business decisions like splits, acquisitions, outsourcing etc etc have enormous impacts not only on the business itself but also on people who are now forced to work with other people/teams who may have different mind-sets, processes and procedures and even completely different technologies. In many such instances strange things will happen and result in a very unpredictable behaviour of compute, network and storage systems. Below I’ll give you such an example where decisions from a systems-level perspective results in massive problems on a storage network.

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1.2 Flow Vision

This subject will be divided in two sections.

  1. Flow Monitor and Generator
  2. Flow Mirror

In FOS 7 the concept of frame-monitoring was introduced on Condor2 and Condor3 ASICs. This allowed an administrator to create a frame template based on the FC frameheader (see here) and obtain statistics on these frames. Flow Vision is somewhat progressing on this technology and has been extended significantly. Flow Vision is a 3 way solution which requires a switch capable of providing the functionality, software licensed to be able to configure and capture flows and a tool to collect and interpret these flows. All Condor 3 based switches (16G), FOS 7.4 and up, and Brocade Network Advisor 12.4.x are needed to be able to fully utilise the base flow-vision functionality. (The Brocade AMP platform is an extension but will be discussed later.)

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