Cisco Blogs
Share

Eliminating Congestion Problems in Storage Area Networks


November 3, 2015 - 0 Comments

Today’s storage area networks (SANs) face tremendous pressure from the phenomenal growth of digital information and the need to access it quickly and efficiently. Worldwide data is projected to multiply by an astonishing 1000 percent by 2020. It’s little wonder, then, that storage administrators rank slow drain and related SAN congestion issues as their number-one concern. If not addressed in a timely fashion, these can have a domino effect, even degrading the performance of totally unrelated applications.

A Slow Drain Device is a device that does not accept frames at the rate generated by the source. In the presence of slow devices, Fibre Channel networks are likely to lack frame buffers, resulting in switch port credit starvation and potentially choking Inter-Switch Links (ISLs). Frames destined for slow devices need to be carefully isolated in separate queues and switched to egress ports without congesting the backplane. A decision then needs to be made about whether the frames are considered stuck and when to drop them.

Cisco provides a Slow Drain Device Detection and Congestion Avoidance (referred to Slow Drain) feature that helps detect, identify, and resolve the condition exhibited by slow devices.

Register Now:

Join us for this live 60-minute webcast and learn the common causes of slow drain and other typical SAN congestion issues. See how Cisco Nexus and MDS switches now include hardware-based congestion detection and recovery logic for precise, fast detection and automatic, real-time resolution.

Watch this Video to learn more: This video demonstrates slow drain diagnostics using Cisco Prime DCNM . See how DCNM can be used to detect Slow Drain devices and troubleshoot the situation within minutes in a large fabric with thousands of ports. Deploy Cisco Prime DCNM today to bring down Slow Drain troubleshooting time from day or weeks to minutes.

Reasons for Slow Drain include:

1) An edge device can be slow to respond for a variety of reasons:  Server performance problems: application or OS, Host bus adapter (HBA) problems: driver or physical failure ,  Speed mismatches: one fast device and one slow device ,  Nongraceful virtual machine exit on a virtualized server, resulting in packets held in HBA buffers , Storage subsystem performance problems, including overload, Poorly performing tape drives

2) Inter Switch Links (ISL) can be slow due to:  Lack of B2B credits for the distance the ISL is traversing and the existence of slow drain edge devices ( in the fabric)
Any device exhibiting such behavior is called a Slow Drain Device. Cisco MDS 9000 Family switches constantly monitor the network for symptoms of slow drain and can send alerts and takes automatic actions to mitigate the situation.  Read this whitepaper to learn more.

Also attend this webinar : Nov 10th, 2015, 8:00 AM PST – Eliminating Congestion Problems in Storage Area Networks

Register Now:

More info:  www.cisco.com/go/mds
Subscribe to youtube Channel:  https://www.youtube.com/user/ciscomds9000

Tony Antony
Sr. Marketing Manager

 

 

In an effort to keep conversations fresh, Cisco Blogs closes comments after 60 days. Please visit the Cisco Blogs hub page for the latest content.