How to Display FC Switches B2B (Buffer to Buffer) Credits

Asset ID:	1-71-1518936.1
Update Date:	2017-06-01
Keywords:

Solution Type Technical Instruction Sure

Solution 1518936.1 : How to Display FC Switches B2B (Buffer to Buffer) Credits

Applies to:

Oracle Fabric Interconnect F1-15 - Version All Versions and later
Oracle Fabric Interconnect F1-4 - Version All Versions and later
Information in this document applies to any platform.

Goal

CS_TIMEOUTs in ESX/ESXi /var/log/vmkernel or /var/log/messages files, what causes these and how to find out more information.

Solution

There could be variety of reasons for Timeouts:

1. Storage is too overwhelmed to respond in time
2. I/O Card is oversubscribed and too busy to process the iocb
3. Low timeout value in the iocb (ESX heartbeat has a timeout value of 3 seconds)
4. FC Credits are too low ( 2X4 has only 3 as opposed to 16 in physical HBA)

Displaying BB_Credit Information for Cisco MDS

To display the BB_credit information, use the show interface bbcredit command (see Example 4-1 and Example 4-2).

Example 4-1 Displays BB_credit Information :

switch# show interface bbcredit

fc2/1 is down (SFP not present)

...

fc2/17 is trunking

Transmit B2B Credit is 255

Receive B2B Credit is 12

Receive B2B Credit performance buffers is 375

12 receive B2B credit remaining

255 transmit B2B credit remaining

fc2/18 is down (SFP not present)

fc2/19 is down (SFP not present)

fc2/20 is down (SFP not present)

fc2/21 is down (Link failure or not-connected)

...

fc2/31 is up

Transmit B2B Credit is 0

Receive B2B Credit is 12

Receive B2B Credit performance buffers is 48

12 receive B2B credit remaining

0 transmit B2B credit remaining

fc2/32 is down (Link failure or not-connected)

Example 4-2 Displays BB_credit Information for a Specified Fibre Channel Interface :

switch# show interface fc2/31 bbcredit

fc2/31 is up

Transmit B2B Credit is 0

Receive B2B Credit is 12

Receive B2B Credit performance buffers is 48

12 receive B2B credit remaining

0 transmit B2B credit remaining

====================================================================================================================================================

On Brocade FC Switches perform:

1. Portstatsshow <portnumber> or <slot/port>

Output will be as follows:

brocade23:admin> portstatsshow 5
stat_wtx 0 4-byte words transmitted
stat_wrx 0 4-byte words received
stat_ftx 0 Frames transmitted
stat_frx 0 Frames received
stat_c2_frx 0 Class 2 frames received
stat_c3_frx 0 Class 3 frames received
stat_lc_rx 0 Link control frames received
stat_mc_rx 0 Multicast frames received
stat_mc_to 0 Multicast timeouts
stat_mc_tx 0 Multicast frames transmitted
tim_rdy_pri 0 Time R_RDY high priority
tim_txcrd_z 0 Time TX Credit Zero (2.5Us ticks)
tim_txcrd_z_vc 0- 3: 0 0 0 0
tim_txcrd_z_vc 4- 7: 0 0 0 0
tim_txcrd_z_vc 8-11: 0 0 0 0
tim_txcrd_z_vc 12-15: 0 0 0 0
er_enc_in 0 Encoding errors inside of frames
er_crc 0 Frames with CRC errors
er_trunc 0 Frames shorter than minimum
er_toolong 0 Frames longer than maximum
er_bad_eof 0 Frames with bad end-of-frame
er_enc_out 0 Encoding error outside of frames
er_bad_os 0 Invalid ordered set
er_rx_c3_timeout 0 Class 3 receive frames discarded due to timeout
er_tx_c3_timeout 0 Class 3 transmit frames discarded due to timeout
er_c3_dest_unreach 0 Class 3 frames discarded due to destination unreachable
er_other_discard 0 Other discards
er_type1_miss 0 frames with FTB type 1 miss
er_type2_miss 0 frames with FTB type 2 miss
er_type6_miss 0 frames with FTB type 6 miss
er_zone_miss 0 frames with hard zoning miss
er_lun_zone_miss 0 frames with LUN zoning miss
er_crc_good_eof 0 Crc error with good eof
er_inv_arb 0 Invalid ARB
open 0 loop_open
transfer 0 loop_transfer
opened 0 FL_Port opened
starve_stop 0 tenancies stopped due to starvation
fl_tenancy 0 number of times FL has the tenancy
nl_tenancy 0 number of times NL has the tenancy
zero_tenancy 0 zero tenancy

On Brocade switches, the buffer credits can be seen with command "portbuffershow"

Example from a Brocade 5100:

sw1:admin> portbuffershow

User Port Lx Max/Resv Buffer Needed Link

Remaining

Port Type Mode Buffers Usage Buffers Distance

Buffers

---- ---- ---- ------- ------ ------- ---------

----------

0 F - 8 8 - -

1 F - 8 8 - -

2 F - 8 8 - -

3 F - 8 8 - -

4 - 8 0 - -

5 - 8 0 - -

6 - 8 0 - -

7 - 8 0 - -

8 - 8 0 - -

9 - 8 0 - -

10 - 8 0 - -

11 - 8 0 - -

12 - 8 0 - -

13 - 8 0 - -

14 - 8 0 - -

15 E LS 246 246 246 60km

16 - 8 0 - -

17 - 8 0 - -

18 - 8 0 - -

19 - 8 0 - -

20 - 8 0 - -

21 - 8 0 - -

22 - 8 0 - -

23 E LE 46 46 46 10km

24 - 8 0 - -

25 - 8 0 - -

26 - 8 0 - -

27 - 8 0 - -

28 - 8 0 - -

29 - 8 0 - -

30 - 8 0 - -

31 - 8 0 - -

32 - 8 0 - -

33 - 8 0 - -

34 - 8 0 - -

35 - 8 0 - -

36 - 8 0 - -

37 - 8 0 - -

38 - 8 0 - -

39 - 8 0 - -

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