Houdini was a master in getting out of these things. Out of a swimming pool with a Straight-Jacket on I mean. This week I had an analogy to his problem. At a customer site Brocade Network Advisor (BNA) became totally unresponsive up to a point where it just stopped.
Tag Archives: brocade
Fillwords IDLE vs ARBff (one last time)
I’ve written about fillwords a lot (see here, here, and here) but I didn’t show you much about the different symptoms an incorrect fillword setting may incur.
As you’ve seen fillwords are a very nifty way of maintaining bit and word-sync on a serial transmission link when no actual frames are sent. Furthermore they also are replaceable with other primitive signals (Like R_RDY, VC_RDY etc) to utilize a very simple instruction method between two ports without interfering with actual frames. That means that fillwords are ALWAYS squeezed in between frames.
Performance expectations with ISL compression
So this week I had an interesting case. As you know the Hitachi arrays have a replication functionality called HUR (Hitachi Universal Replicator) which is an advanced a-synchronous replication solution offered for Mainframe and OpenSystems environments. HUR does not use a primary to secondary push method but rather the target system is issuing reads to the primary array after which this one sends the required data. This optimizes the traffic pattern by using batches of data. From a connectivity perspective you will mostly see full 2K FC frames which means on long distance connections (30KM to 100KM) you can very effectively keep a fairly low number of buffer-credits on both sides whilst still maintain optimum link utilization.
Brocade ramps up SDN knowledge with heavy-weight Colin Dixon
Colin Dixon, most notably known for contributions in the open source world on the networking side of the fence has decided to team up with Brocade. Let me rephrase that: started working for them. This is a significant testimony that Brocade is taking SDN serious in two ways.
Brocade MAPS “non-management”
Ok this may seem a bit of me having a go at Brocade’s successor to Fabric Watch but it isn’t. This week I ran into a couple of cases where switches were upgraded to FOS 7.2.x and Fabric Watch was converted to MAPS. Nothing wrong with that but it seems that many administrators blindly kick off some rule-sets via BNA and leave it at that. Whilst I applaud the move to the latest and greatest code levels (mainly because the majority of known bugs are fixed) it also means that updated and/or new functionality needs to be reviewed and actively managed.
Energy Efficient Fibre Channel and related cost savings
For years many storage environments have used both active-active and active-passive multipath (MPIO) access mechanisms to access storage arrays in a dispersed or linear method. On enterprise class storage arrays with global caches the active-active method is most often used while on modular arrays you’ll see the active-passive scenario often applied. Inherently this means that during absence of IO, whether being the passive path or due to total non-IO operations (ie. there is no application or operating system sending or receiving any data), the actual fibre-channel links are only sending IDLE or ARB(ff) fillwords to maintain bit- and word synchronization. This also means that both the sender and receiver are always up and thus use the same amount of power as where they transmitting data at full line-rate. Obviously this is a waste of scarce resources and this is what has been addressed in the new FC standards that are coming up. The FC framing and signalling standard will be enhanced to have traffic diagnostics determine if an SFP should be in full power operating power or in a power reduced mode. Below are the details including some cost-savings calculations.
Time with and without NTP on FC switches
I’ve been writing about troubleshooting issues for a while now and one of the things that is very difficult and most time consuming is correlating events between host systems, switches and storage arrays in the even of storage related errors. My advice has always been the same. Hook everything up to NTP systems, make sure that time and date settings, including time-zones and DST settings do fall within the drift values of the NTP client and that little nifty piece of software will make sure time is equal on all systems. (See below how to accomplish this.)
There are however some issues when this is not fully followed through and virtual switches are used.
Defzone configuration
Today I came across a case where the administrator had a bit of an incorrect interpretation of the term “defzone“. Brocade uses defzone in case when no normal zoning configuration is active. A defzone (default zone) is a hidden “dummy” zoning configuration with no members(*). No WWN’s, aliases or port-ID’s ever will be added to a “defzone”.
Brocade Fabric Vision – Version 1
As you may have read in my previous posts I’m not really a fan of marketing driven terminology whereby existing technology is re-branded over and over again in order to obfuscate the underlying technology and make things more complex that they really are. The FC Gen-X nonsense is one of them. With Brocade Fabric Vision it took me a while however I see where Brocade is going with this and more where it is coming from.
Brocade 65xx series and airflow
This is important!! Now, you would think that when you look at the weather channel and the person tells you there is a wind coming from the North the direction is from North to South. This could be interpreted somewhat different when he or she tells you there is a “northerly” wind. Does the later mean it’s coming from the North or is it going to the North. The same is now true for Brocade 65xx series switches. The 6505/6510 have a different interpretation of how the wind blows than the 6520 series. Is it moving forward or reverse, is it coming from the front or back and on which side is the intake and/or exhaust and which spare-part do you need to order in case one fails, xx-F or xx-R. If you order the wrong one the switch will tell your this after which it will shut down. Whoops. The documentation also shows some confusion around the PS acronym. Is it now related to the airflow, in which case it stands for Port-Side, or does it mean Power Supply when a FRU is meant?