Automated Testing

Hi all,

Transfer Speed between our zDT and local pc are so poor. I ask to some colleague from Linux team and seemingly is not related with Linux SO. However they send me this detail:

Communication between zDT and Linux Server is going through virtual interface tap0

serverL:/ # ethtool tap0

Settings for tap0:

        Supported ports: [ ]

        Supported link modes:   Not reported

        Supported pause frame use: No

        Supports auto-negotiation: No

        Supported FEC modes: Not reported

        Advertised link modes:  Not reported

        Advertised pause frame use: No

        Advertised auto-negotiation: No

        Advertised FEC modes: Not reported

        Speed: 10Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 0

        Transceiver: internal

        Auto-negotiation: off

        MDI-X: Unknown

        Current message level: 0xffffffa1 (-95)

                               drv ifup tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000

        Link detected: yes

serverL:/ #

 It is possible that issue is related with value: Speed: 10Mb/s 

¿It is possible to modify that value? 

Thanks in advance.

Hi all,

I am into task to transfer a large number of heavy files from my PC to z/OS.( zDT)

Transfer Speed between our zDT and local pc are so poor. I ask to some colleague from Linux team and seemingly is not related with Linux SO. However they send me this detail:

Communication between zDT and Linux Server is going through virtual interface tap0

serverL:/ # ethtool tap0

Settings for tap0:

        Supported ports: [ ]

        Supported link modes:   Not reported

        Supported pause frame use: No

        Supports auto-negotiation: No

        Supported FEC modes: Not reported

        Advertised link modes:  Not reported

        Advertised pause frame use: No

        Advertised auto-negotiation: No

        Advertised FEC modes: Not reported

        Speed: 10Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 0

        Transceiver: internal

        Auto-negotiation: off

        MDI-X: Unknown

        Current message level: 0xffffffa1 (-95)

                               drv ifup tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000

        Link detected: yes

serverL:/ #

 It is possible that issue is related with value: Speed: 10Mb/s 

¿It is possible to modify that value? 

Thanks in advance.

------------------------------
Juan Carlos Delgado
------------------------------

From the documentation:

At the time of writing, we were aware of two specific problems that might impact OSA
performance.

If frames larger than expected are used, an excessive number of frames might be dropped
(causing a retransmission). This might not be noticed unless careful measurements or
comparisons are made. We believe this problem is resolved by including the sysctl
parameter that is now recommended:

net.core.rmem_max=1048576

Linux attempts to offload various low-level LAN interface functions to the NIC adapter. This
might not be compatible with the awsOSA implementation and can result in drastic
performance degradations. We note that more recent Linux distributions might not
experience these problems.

IBM does not provide performance specifications for ISV zPDT OSA. When working correctly,
informal observation indicates that FTP throughput might be in the 5 - 20 MBps26 (megabytes
per second) range, assuming an unconstrained network in a dedicated environment. If your
performance is very much worse than this, consider experimenting with the ethtool
commands described here.

One or more of the following commands, intended to disable the Linux offloading of IP
functions, might improve the situation:

# ethtool -K eth0 rx off (disable RX checksumming offload)
# ethtool -K eth0 tso off (disable TCP segmentation offload)
# ethtool -K eth0 gso off (disable generic segmentation offload)
# ethtool -K eth0 gro off (disable generic RX offload)
# ethtool -K eth0 lro off (disable large RX offload)
# ethtool -K eth0 rxvlan off (if you are using VLANs)
# ethtool -k eth0 (display status of NIC)
# ethtool -S eth0 (display statistics)
# ethtool -K em1 rx off (newer style of NIC naming)
# ethtool -K enp0s25 rx off (newer style of NIC naming)

You might need to experiment with these commands. One user reported the following
combination most effective for his system.

# ethtool -K eth0 rx off
# ethtool -K eth0 gso off
# ethtool -K eth0 gro off
# ethtool -K eth0 rxvlan off

We suspect that effective combinations of these options differ with various Linux levels and
with various NIC adapters.

Sebastian

Hi all,

I am into task to transfer a large number of heavy files from my PC to z/OS.( zDT)

Transfer Speed between our zDT and local pc are so poor. I ask to some colleague from Linux team and seemingly is not related with Linux SO. However they send me this detail:

Communication between zDT and Linux Server is going through virtual interface tap0

serverL:/ # ethtool tap0

Settings for tap0:

        Supported ports: [ ]

        Supported link modes:   Not reported

        Supported pause frame use: No

        Supports auto-negotiation: No

        Supported FEC modes: Not reported

        Advertised link modes:  Not reported

        Advertised pause frame use: No

        Advertised auto-negotiation: No

        Advertised FEC modes: Not reported

        Speed: 10Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 0

        Transceiver: internal

        Auto-negotiation: off

        MDI-X: Unknown

        Current message level: 0xffffffa1 (-95)

                               drv ifup tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000

        Link detected: yes

serverL:/ #

 It is possible that issue is related with value: Speed: 10Mb/s 

¿It is possible to modify that value? 

Thanks in advance.

------------------------------
Juan Carlos Delgado
------------------------------

Hello Sebastian, thanks for your time.

I check that almost all parameters are "off". I tried some command and I get: Cannot set device feature settings: Operation not permitted

From the documentation:

At the time of writing, we were aware of two specific problems that might impact OSA
performance.

If frames larger than expected are used, an excessive number of frames might be dropped
(causing a retransmission). This might not be noticed unless careful measurements or
comparisons are made. We believe this problem is resolved by including the sysctl
parameter that is now recommended:

net.core.rmem_max=1048576

Linux attempts to offload various low-level LAN interface functions to the NIC adapter. This
might not be compatible with the awsOSA implementation and can result in drastic
performance degradations. We note that more recent Linux distributions might not
experience these problems.

IBM does not provide performance specifications for ISV zPDT OSA. When working correctly,
informal observation indicates that FTP throughput might be in the 5 - 20 MBps26 (megabytes
per second) range, assuming an unconstrained network in a dedicated environment. If your
performance is very much worse than this, consider experimenting with the ethtool
commands described here.

One or more of the following commands, intended to disable the Linux offloading of IP
functions, might improve the situation:

# ethtool -K eth0 rx off (disable RX checksumming offload)
# ethtool -K eth0 tso off (disable TCP segmentation offload)
# ethtool -K eth0 gso off (disable generic segmentation offload)
# ethtool -K eth0 gro off (disable generic RX offload)
# ethtool -K eth0 lro off (disable large RX offload)
# ethtool -K eth0 rxvlan off (if you are using VLANs)
# ethtool -k eth0 (display status of NIC)
# ethtool -S eth0 (display statistics)
# ethtool -K em1 rx off (newer style of NIC naming)
# ethtool -K enp0s25 rx off (newer style of NIC naming)

You might need to experiment with these commands. One user reported the following
combination most effective for his system.

# ethtool -K eth0 rx off
# ethtool -K eth0 gso off
# ethtool -K eth0 gro off
# ethtool -K eth0 rxvlan off

We suspect that effective combinations of these options differ with various Linux levels and
with various NIC adapters.

Sebastian

Hi all,

I am into task to transfer a large number of heavy files from my PC to z/OS.( zDT)

Transfer Speed between our zDT and local pc are so poor. I ask to some colleague from Linux team and seemingly is not related with Linux SO. However they send me this detail:

Communication between zDT and Linux Server is going through virtual interface tap0

serverL:/ # ethtool tap0

Settings for tap0:

        Supported ports: [ ]

        Supported link modes:   Not reported

        Supported pause frame use: No

        Supports auto-negotiation: No

        Supported FEC modes: Not reported

        Advertised link modes:  Not reported

        Advertised pause frame use: No

        Advertised auto-negotiation: No

        Advertised FEC modes: Not reported

        Speed: 10Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 0

        Transceiver: internal

        Auto-negotiation: off

        MDI-X: Unknown

        Current message level: 0xffffffa1 (-95)

                               drv ifup tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000

        Link detected: yes

serverL:/ #

 It is possible that issue is related with value: Speed: 10Mb/s 

¿It is possible to modify that value? 

Thanks in advance.

------------------------------
Juan Carlos Delgado
------------------------------

Hi all,

I am into task to transfer a large number of heavy files from my PC to z/OS.( zDT)

Transfer Speed between our zDT and local pc are so poor. I ask to some colleague from Linux team and seemingly is not related with Linux SO. However they send me this detail:

Communication between zDT and Linux Server is going through virtual interface tap0

serverL:/ # ethtool tap0

Settings for tap0:

        Supported ports: [ ]

        Supported link modes:   Not reported

        Supported pause frame use: No

        Supports auto-negotiation: No

        Supported FEC modes: Not reported

        Advertised link modes:  Not reported

        Advertised pause frame use: No

        Advertised auto-negotiation: No

        Advertised FEC modes: Not reported

        Speed: 10Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 0

        Transceiver: internal

        Auto-negotiation: off

        MDI-X: Unknown

        Current message level: 0xffffffa1 (-95)

                               drv ifup tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000

        Link detected: yes

serverL:/ #

 It is possible that issue is related with value: Speed: 10Mb/s 

¿It is possible to modify that value? 

Thanks in advance.

------------------------------
Juan Carlos Delgado
------------------------------

Hi all,

I am into task to transfer a large number of heavy files from my PC to z/OS.( zDT)

Transfer Speed between our zDT and local pc are so poor. I ask to some colleague from Linux team and seemingly is not related with Linux SO. However they send me this detail:

Communication between zDT and Linux Server is going through virtual interface tap0

serverL:/ # ethtool tap0

Settings for tap0:

        Supported ports: [ ]

        Supported link modes:   Not reported

        Supported pause frame use: No

        Supports auto-negotiation: No

        Supported FEC modes: Not reported

        Advertised link modes:  Not reported

        Advertised pause frame use: No

        Advertised auto-negotiation: No

        Advertised FEC modes: Not reported

        Speed: 10Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 0

        Transceiver: internal

        Auto-negotiation: off

        MDI-X: Unknown

        Current message level: 0xffffffa1 (-95)

                               drv ifup tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000

        Link detected: yes

serverL:/ #

 It is possible that issue is related with value: Speed: 10Mb/s 

¿It is possible to modify that value? 

Thanks in advance.

------------------------------
Juan Carlos Delgado
------------------------------