Ok, truth be told it is not a Flow Vision bug but in FOS 9.0.0 it is flagged as such under defect 653188. As you know Flow Vision can be configured to monitor certain traffic flows. SCSI commands such as read, write, xfer-rdy,, status etc can be viewed with the flow –show command.
Interesting Flow Vision bug Read More »
Where did my disks go? So now and then you may run into an issue which cannot be explained properly by just looking at the standard events that show up in \”/var/log/messages\”. Issues such as Oct 7 18:24:20 centos8 kernel: lpfc 0000:81:00.0: 0:1305 Link Down Event xc received Data: xc x20 x800110 x0 x0 Oct
Enabling Verbose Logging on Linux with Emulex Host Bus Adapters Read More »
Whenever you\’ve encountered an output of a nameserver entry you may have come across the phenomenon that the fabric has no clue what the attached device is. For a FC switch an attached device (or N-port in technical terms) is not more than a source or destination where frames originate from or can be sent
Initiator, Target, Both or None ?? Read More »
FDMI stands for Fabric Device Management Interface and is such an enormously cool feature and unfortunately one of the least used. From an operational management perspective FDMI provides a wealth of information to the fabric regarding the attached devices. The thing that flabbergasted me is that almost no device (HBA/Array) has this turned on of
Why FDMI is compulsory (or should be!!) Read More »
Storage networks have been used for disaster recovery and business continuity purposes for as long as fibre-channel existed. The moment arrays could communicate to other arrays over either short or long distances replication software has been developed and incorporated in firmware so that data could be copied to remote sites.
9 – Long Distance configurations Read More »
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
Fillwords IDLE vs ARBff (one last time) Read More »
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
Energy Efficient Fibre Channel and related cost savings Read More »
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
Time with and without NTP on FC switches Read More »
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
Brocade 65xx series and airflow Read More »
The FC frame header has not changed since its inception back in the late 80-ies. This shows the absolute rock-solid backward compatibility towards previous generation platforms and vendors. Obviously the the FC protocol itself has grown and evolved with marked demands to provide an extremely flexible transport mechanism for the most demanding storage environments. When
FC Frame header, or is there more to it Read More »
