Fibre Channel (SAN)

Reply
New Contributor
Posts: 4
Registered: ‎10-24-2017

If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

I have a strage problem which made me to draft the issue here and get the similar experience if anyone has faced it.

We have two fabric as below:-

FabA:- Core Switch (brocade 4200) Where host is connected and another switch (brocade 6520) where Storage FA port connected.

We have two ISL ports connected between these two switches.

FabB:- Same setup as above.

 

Issue caused:- one of the ISL port went faulty and triggered number of errors on all fields including CRC. We left it as it for SFP/cable replacement. after exactly two days of the issue. One of the Host lost SAN disks connectivity.

 

Can this redundant ISL port cause the SAN disks lost connectivity. We then immediately disabled this one ISL port just to rule out.

But Really wanted to know the impact levels out of it. 

External Moderator
Posts: 5,033
Registered: ‎02-23-2004

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

@ksravanreddy786

 

there is no Brocade 4200.

 

do you mean Brocade 4100 ?

 

can you please post from command line from output "switchshow"

 

the Line "SwitchType"

 

what is the FOS installed on both Brocade 6520 and this Brocade 4x00 ????

 

 

TechHelp24
New Contributor
Posts: 4
Registered: ‎10-24-2017

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

Oh yes. Its Brocade 4020. The 0 port which we disabled later after the issue caused. but there is a redundant ISL connection i.e. port 15 here in this switch. 

 

switchType: 37.1
switchState: Online
switchMode: Native
switchRole: Principal
switchDomain: 13
switchId: fffc0d
switchWwn: 10:00:00:05:1e:09:20:5f
zoning: ON (Switch5Config)
switchBeacon: OFF

Area Port Media Speed State Proto
=====================================
0 0 id N4 No_Light Disabled

15 15 id N4 Online E-Port 10:00:00:27:f8:c6:ae:d3 "Fab1-Switch2" (downstream)

External Moderator
Posts: 5,033
Registered: ‎02-23-2004

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

from you first Post:

 

--->>>We have two fabric as below:-

--->>>FabA:- Core Switch (brocade 4200)

 

what is the FOS release?  please post both, 4020 and 6520

 

4020 must meet a min. required FOS 6.2.2 in order to ISL with 6520 with FOS 7.x,

FOS 8.x is not longer comaptible with FOS 6

 

QoS must be disable on 16G Platforms whe ISL with FOS 6.2.2e or earlier otherwise the ISL segmented

 

 

TechHelp24
New Contributor
Posts: 4
Registered: ‎10-24-2017

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

4020 FOS:-
Kernel: 2.6.14.2
Fabric OS: v6.2.2g
Made on: Mon Feb 2 13:31:02 2015
Flash: Sun May 28 00:16:08 2017
BootProm: 4.6.6

6520 FOS:-
Kernel: 2.6.14.2
Fabric OS: v7.4.1d
Made on: Thu Jul 14 19:07:36 2016
Flash: Sat Jul 1 21:10:07 2017
BootProm: 1.0.16
External Moderator
Posts: 5,033
Registered: ‎02-23-2004

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

with FOS Release you are in range

 

when you say One of the ISL port is down, are those both Port configured as Trunking or simple ISL Port ?

 

is probable by simple ISL one port freeze and the Traffic was active only on the second port that become fault, and for this reason the host lost a connectivity to Storage/LUN.

 

 

 

 

 

TechHelp24
New Contributor
Posts: 4
Registered: ‎10-24-2017

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

After the ISL port became faulty and passed two days. then host lost connectivity. Its not immediately. 

Brocade Moderator
Posts: 414
Registered: ‎03-29-2011

Re: If one of the ISL redundant port is down in one Fabric. Will it make a host to loose all SAN LUNs

Hi,

 

the CRC on ISL will, over time,  corrupt too many frames to / from the host / storage so the MPIO software on the host will assume that the path(s) to disk is failed (probably). Will need the host logs / MPIO for troubleshooting this in detail. To further confuse the MPIO software, the name server will still contain the storage port (port is online and reachable but only partly).... 

 

What you see is one reason for using port fencing or disabling links with physical issue as fast as possible. Also, historically, the once the degation (physical) of the links have started, it is getting worse. So, you might just have one or two CRC per hours first, but in 1-2-4 days, you will get an higher count.  Another reason to disable the port, assume you have enough redunacny in your network, of course.




If this provided you with a solution to this issue, please mark it with the button at the bottom "Accept as solution".


Any and all information provided by me is not reviewed, approved or endorsed by Brocade and is provided solely as a convenience for Brocade customers. All systems and all networks are different and unique. If you have a service affecting network problem, please open a TAC service request for service through Brocade, or through your OEM equipment provider. If this provided you with a solution to this issue, please mark it with the button at the bottom "Accept as solution"

Join the Community

Get quick and easy access to valuable resource designed to help you manage your Brocade Network.

vADC is now Pulse Secure
Download FREE NVMe eBook