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Find Physical Layer Problems

Find Physical Layer Fibre Channel Problems

Connectivity is the ability of devices to clearly communicate with other devices on a network. Most SAN’s will have periods of connectivity events that occur because of occasional maintenance, when cables are pulled and equipment gets shut down or rebooted.  These events are acceptable as long as they can be attributed to an action that had been taken.

 

Important disruptions to connectivity can be identified by the following events:

  • CRC error
  • CV error
  • Frame error
  • CRC
  • Abort
  • Fabric Login and Logout
  • Class 3 discard
  • Basic link services
  • SCSI Bad Status
  • SCSI Check Condition

Every environment that Virtual Instruments has ever instrumented has been shown to have errors present that were forcing the servers to resend data requests or retry data access. Often, things like aborts, CRC’s, class 3 discards, unnecessary logins, failed SCSI transactions, etc. are present on an infrastructure that hasn’t been instrumented. Instrumentation allows the events to be addressed in a timely methodical manner rather than as part of a critical issue when enough events combine to cause impact.

Best practice is to find and eliminate physical layer errors, before moving on to other issues.

Physical layer errors are errors that exist on the FC1 layer. Code Violations (CV); Loss of Sync (LoS); and Frame Error metrics can all be used to find physical layer issues. These are very basic primitive metrics that can let you know when something as simple as a cable was pulled or a transceiver has lost its light. Something as simple as a pulled FC cable will create a massive number of CV errors.

VirtualWisdom®, by accessing the data from the SANInsight® hardware monitoring devices, is the only product that can monitor and alert on storage access times, network/port congestion, link errors, CRC errors, and SCSI errors, and generate historical trend reports that show the behavior of a heterogeneous SAN, over time.  This information helps to dramatically expedite storage troubleshooting.  With the hardware-level monitoring of SANInsight Taps and Probes, IT staff can quickly and dependably focus on the offending components, saving time, and more quickly resolving trouble tickets.

The following sample VirtualWisdom report shows links that are experiencing physical layer issues.

Port Number

Attached Port WWN

Channel

Attached Port Name

CRC Errors

54

1005550c947678

Ch 2

Server_6267t13

5

163

40060e447a7f03

Ch 2

Array1_Port02

4

551

3100e08b9246de

Ch 2

Server_613s13

2

19

600e80047e7f41

Ch 2

Array1_Port31

1

Figure 1:  Connectivity and Errors Report – Physical Layer Errors

To learn more about how Virtual Instruments can help you find and fix physical layer SAN problems, contact us today.

Case Study

  • Mobile Data Services | Leading world-wide supplier of mobile data solutions deploys a VirtualWisdom solution to monitor its SAN to help ensure 100% data availability. Software probe is used to help provide visibility into the Fibre Channel SAN on an ongoing basis to help avoid application slowdowns.

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Datasheet

  • SANInsight Fibre TAP Patch Panel System | Virtual Instrument’s new SANInsight TAP Patch Panel System provides a range of options for integrating the unique, patented technology into patch panels. By unifying TAP and patch functions into a single layer of physical infrastructure, SANInsight significantly reduces the cost, complexity, and infrastructure impact of TAP deployment. SANInsight facilitates the broad installation of TAPs into both new and existing physical infrastructures, fully addressing the best practices monitorability requirement and enabling complete SAN optimization.

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Whitepaper

  • Twelve Ways that Virtual Instruments Enhances your Existing Virtual Infrastructure and SAN Management Tools | January 2010 | The only hope of solving today's virtualized data center challenges is with better management tools. Today's most common solutions such as Enterprise Management Frameworks, Storage Resource Management, and specialized element managers all lack physical, real-time monitoring of the IO path. Virtual Infrastructure Optimization solutions, such as VirtualWisdom, are the only products that can non-intrusively optimize the performance of applications, including virtualized applications, in continuous real-time by measuring actual SAN I/O traffic data.

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Videos & Podcasts

  • Finding physical layer FC SAN problems | In this short VirtualWisdom video, we demonstrate how the storage administrator can quickly and easily find physical layer problems, such as CRC errors, loss of sync, loss of signal, and frame errors. Finding physical layer issues and remediating them can often avoid application slowdowns or outages.