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CISCO MDS switch port unavailable

Patrick M
Level 1
Level 1

Hi there,

I have a backup project i am carrying out for our customer. we have had an issue with Cisco MDS FC switch zoned with a tape library and SAN storage.

Every time i run a backup to tape, the FC ports on the tape drive go offline, the FC ports on the switch go offline as well. When i change the cabling on the Cisco switch,the ports on the drive work for a while and then goes offline again.

Please advice if there are any performance configurations to run in the cisco switch since i am backing up TBs of data?

 

Your help will be appreciated.

 

regards,

Patrick

5 Replies 5

Walter Dey
VIP Alumni
VIP Alumni

What is the status of the port in the down state ?

error disable ?

post show port counters

will the port come up again, or do you disable / enable port ?

hi wdey,

the ports are showing errDisable, i have disabled and enabled ports and the backup is running..

how do i resolve this permanently?

 

regards,

Patrick

 

see eg.

http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html#topic3

Do you see a console / syslog message which should indicate the cause of the errdisable ?

I guess this must be a physical link issue: cable, port, transceiver; do you see crc error counter going up ?

 

Hi wdey,

this is the port status when it goes offline:

SW01# sh int fc1/27
fc1/27 is down (Error disabled - bit error rate too high)
    Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
    Port WWN is 20:1b:54:7f:ee:e2:8d:00
    Admin port mode is auto, trunk mode is on
    snmp link state traps are enabled
    Port vsan is 2
    Receive data field Size is 2112
    Beacon is turned off
    5 minutes input rate 0 bits/sec, 0 bytes/sec, 0 frames/sec
    5 minutes output rate 0 bits/sec, 0 bytes/sec, 0 frames/sec
      263045 frames input, 12907156 bytes
        0 discards, 0 errors
        0 CRC,  0 unknown class
        0 too long, 0 too short
      4308477 frames output, 8677425352 bytes
        1 discards, 0 errors
      2 input OLS, 2 LRR, 0 NOS, 3 loop inits
      5 output OLS, 2 LRR, 1 NOS, 3 loop inits
    Interface last changed at Mon Oct 13 07:36:46 2014

 

There is this link: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/mds9000/sw/4_1/configuration/guides/cli_4_1/clibook/intf.html#wp1151733

I referred to the customer to this link on disabling, bit-rate error threshold but the customer is concerned about any disruption on Production Storage (there is a redundant MDS with redundant connectivity to production storage).

does disabling bit-rate affect performance/availability of the switch?

 

patrick

I would investigate what the real problem is; disabling bit-error threshold is bad; in the end, you will have to retransmit the broken FC frames, which will severly impact the performance.

Is this port actually a F-Port ?

switch# show interface 

fc1/1 is up

    Hardware is Fibre Channel, SFP is short wave laser

    Port WWN is 20:0b:00:05:30:00:8d:de

    Admin port mode is F

    Port mode is F, FCID is 0x610000

    Port vsan is 2
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