Meaning of output from scacp

[MarkOfAus]

Hi all,

Here is the output of "scacp show lan" on 7.3-2 machine, clustered:
Device Errors + Mgt Buffer MgtMax Line Total Current
Device Type Events Status Priority Size BufSiz Speed Pkts(S+R) LAN Address
------ ---- ------ ------ -------- ---- ------ ----- --------- -----------
LCL 0 Run Online Local Restart 0 1426 0 N/A 215858 00-00-00-00-00-00
EIA 82559 72 Run Online Restart -3 1426 0 100 102775206 AA-00-04-00-05-04
EWA DEGXA 11 Run Online Restart 10 1426 0 1000 301676325 00-17-A4-3D-DF-7F
EWB DEGXA 7 Run Online Restart 5 8120 0 1000 147026381 00-17-A4-3D-CF-0A


(If you can't read from this horrible formatting, the "buffer size" for the EWA device is 1426, for the EWB device it is 8128)

What I would like to know is what is the "Buffer Size" column?

Why do the two ewa and ewb have different "buffer sizes" when they are the same cards?

Do I trust VMS has got this "buffer size" correct?

A lancp sho dev/char ewa and ewb show that they have the same minimum and maximum receive buffers.

The only clue, perhaps, is that ewa is a fibre-connected (nic to fibre-converter) whereas ewb is connected into the lan and therefore using a switch?

EWA has jumbo frames enabled, EWB did, but they have been disabled since a reboot.

Any information would be helpful.

Regards
Mark

[Volker Halle · Accepted solution]

Mark,

the 'buffer size' is most likely the useable buffer size for the SCA protocol. Are you sure about JUMBO frames and EWA/EWB ? Could it be the other way around ?

What does ANAL/SYS and SDA> SHOW LAN/FULL give a Receive buffer size for these LAN interfaces ?

Volker.

[Robert Gezelter]

Mark,

I would tend to agree with Volker that EWB has jumbo frame support enabled.

The original Ethernet specification has a lower limit of 1500 bytes/frame (see the actual specification, for the precise contents).

Gigabit Ethernet permits so-called "Jumbo frames", up to 9000 bytes in size.

- Bob Gezelter, http://www.rlgsc.com

[MarkOfAus]

Volker,

I attached the voluminous output of sda show lan, but have also included a bit of data in this reply (the part that shows the buffers).

"the 'buffer size' is most likely the useable buffer size for the SCA protocol. Are you sure about JUMBO frames and EWA/EWB ? Could it be the other way around ?"

Both devices were jumbo, now only ewa is:

Output from lancp (driver messages portion):
EWA
---
18-FEB-2008 20:53:28.79 Link up: 1000 mbit, full duplex, flow control disabled
18-FEB-2008 20:53:25.56 Link down
18-FEB-2008 13:12:07.47 Link up: 1000 mbit, full duplex, flow control disabled
18-FEB-2008 13:12:04.23 Link down
18-FEB-2008 13:12:04.23 Jumbo frames enabled
18-FEB-2008 13:10:16.17 Link up: 1000 mbit, full duplex, flow control disabled
18-FEB-2008 13:10:12.86 Device type is BCM5703C (UTP) Rev A0 (11000000)
18-FEB-2008 13:10:12.85 DEGXA-TB located in 64-bit, 33-mhz PCI slot
18-FEB-2008 13:10:12.85 Auto-negotiation mode set by console (EGA0_MODE)
S

And EWB:
--------

18-FEB-2008 20:57:56.38 Link up: 1000 mbit, full duplex, flow control (recv)
18-FEB-2008 20:57:53.25 Link down
18-FEB-2008 20:57:53.25 Jumbo frames disabled
18-FEB-2008 15:39:49.46 Link up: 1000 mbit, full duplex, flow control (recv)
18-FEB-2008 15:39:49.14 Link down
18-FEB-2008 15:39:45.62 Link up: 1000 mbit, full duplex, flow control (recv)
18-FEB-2008 15:26:02.39 Possible duplex mode mismatch condition detected
18-FEB-2008 14:25:26.44 Possible duplex mode mismatch condition detected
18-FEB-2008 13:25:06.84 Possible duplex mode mismatch condition detected
18-FEB-2008 13:25:01.69 Link up: 100 mbit, half duplex, flow control disabled
18-FEB-2008 13:24:49.83 Link down
18-FEB-2008 13:18:40.03 Link up: 1000 mbit, full duplex, flow control (recv)
18-FEB-2008 13:15:51.47 Link down
18-FEB-2008 13:12:07.38 Link up: 1000 mbit, full duplex, flow control (recv)
18-FEB-2008 13:12:04.23 Link down
18-FEB-2008 13:12:04.23 Jumbo frames enabled
18-FEB-2008 13:10:16.07 Link up: 1000 mbit, full duplex, flow control (recv)
18-FEB-2008 13:10:12.90 Device type is BCM5703C (UTP) Rev A0 (11000000)
18-FEB-2008 13:10:12.89 DEGXA-TB located in 64-bit, 33-mhz PCI slot
18-FEB-2008 13:10:12.89 Auto-negotiation mode set by console (EGB0_MODE)



"What does ANAL/SYS and SDA> SHOW LAN/FULL give a Receive buffer size for these LAN interfaces ?"

-- EWA Device Information (cont) 20-FEB-2008 08:38:48 --

Put rcv ptr/index 00000000 Get rcv ptr/index 000003E1
Put xmt ptr/index 000000D9 Get xmt ptr/index 000000D9
Put cmd ptr/index 00000121 Get cmd ptr/index 00000000
Put uns ptr/index 00000008 Get uns ptr/index 00000000
Put smt ptr/index 00000000 Get smt ptr/index 00000000
RBufs owned by dev 328 Rcv packet limit 128
XEnts owned by dev 0 XEnts owned by host 512
CEnts owned by dev 0 Transmit timer 0
UEnts owned by dev 0 Control timer 0
SEnts owned by dev 0 Periodic SYSID timer 621
Current rcv buffers 328 Ring unavail timer 0
Rqst MAX rcv buffers 256 USB timer 144
Rqst MIN rcv buffers 128 Receive alignment 0
Curr MAX rcv buffers 264 Receive buffer size 1518
Curr MIN rcv buffers 264 Min 1st chain segment 0
FILL rcv buffers 264 Min transmit length 0
ADD rcv buffers 328 Dev xmt header size 0


-- EWB Device Information (cont) 20-FEB-2008 08:40:23 --

Put rcv ptr/index 00000000 Get rcv ptr/index 00000144
Put xmt ptr/index 000001E9 Get xmt ptr/index 000001E9
Put cmd ptr/index 00000083 Get cmd ptr/index 00000000
Put uns ptr/index 00000008 Get uns ptr/index 00000000
Put smt ptr/index 00000000 Get smt ptr/index 00000000
RBufs owned by dev 327 Rcv packet limit 128
XEnts owned by dev 0 XEnts owned by host 512
CEnts owned by dev 0 Transmit timer 0
UEnts owned by dev 0 Control timer 0
SEnts owned by dev 0 Periodic SYSID timer 675
Current rcv buffers 327 Ring unavail timer 0
Rqst MAX rcv buffers 256 USB timer 48
Rqst MIN rcv buffers 128 Receive alignment 0
Curr MAX rcv buffers 264 Receive buffer size 1518
Curr MIN rcv buffers 264 Min 1st chain segment 0
FILL rcv buffers 264 Min transmit length 0
ADD rcv buffers 328 Dev xmt header size 0



Regards,
Mark

[MarkOfAus]

Robert,

"I would tend to agree with Volker that EWB has jumbo frame support enabled."

And so would I! :-)
The problem is when both were set to jumbo, the buffer sizes were as they are now. When one is changed, the buffer sizes remain the same. Ergo, it would seem buffer sizes have nothing to do with jumbo frames?


"The original Ethernet specification has a lower limit of 1500 bytes/frame (see the actual specification, for the precise contents).

Gigabit Ethernet permits so-called "Jumbo frames", up to 9000 bytes in size."

That is why, when I removed jumbo frames from the lan connected device because of switch incompatibility, I expected to notice the buffer change.


Regards,
Mark.

[MarkOfAus]

I apologise for late replies, but ITRC has been playing silly buggers for the last 24 hours; at least in my "end of town".

[Volker Halle]

Mark,

as the system has not been rebooted after disabling Jumbo frames on EWB, I would expect that SCACP> SHOW LAN still reflects the setting seen at boottime.

SCACP> SHOW CHANNEL should show you the current buffer size being used and that should be the same value as for EWA.

SCA will always try to use the biggest possible buffer size on the channel between any 2 nodes and it will also reduce the size, if the equipment on the LAN path does not support larger buffer sizes.

You can see the current, remote, local and negotiated buffer sizes with SDA:

$ ANAL/SYS
SDA> SHOW PORT
...
SDA> SHOW PORT/ADDR=pe_pdt/CHAN/VC

Look for Active Channel and 'Buffer Size' on the righthand side of the display.

Volker.

[Volker Halle]

Mark,

interestingly, the EWB counter for Jumbo transmits is 44, whereas the same counter for EWA is 0. I doubt that EWA is actually sending or receiving Jumbo frames.

What's the setting of NISCS_MAX_PKTSZ ?

Volker.

[Wim Van den Wyngaert]

Note for the SCA part in the enclosure :

EWA
Maximum buffer size 1498

EWB
Maximum buffer size 8998

Wim

[Wim Van den Wyngaert]

I know nothing about Jumbo's but
EWB also has a low number of collisions.

It tried to use jumbo's but failed ?

Is the stuff between the cluster nodes jumbo ready ?

Wim