Dell EqualLogic PS6210XS EqualLogic PS Series Storage Arrays iSCSI Initiator a - Page 21

Con Linux Networking

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which can place a resource burden on both the EqualLogic arrays and the Linux host. Dell recommends that you change the setting to manual. The HIT/Linux eqltune utility recommends this change, but does not automatically implement it. node.startup = manual Configure Linux Networking Dell recommends that you configure multipathing for Ethernet interfaces on a Linux host to connect to an EqualLogic group. This configuration of multiple NICs per subnet requires that several Linux networking parameters be modified from their default values for reliable implementation. The HIT/Linux eqltune utility, when run in fix mode, will automatically configure the Linux operating system to operate correctly with this configuration. NOTE: Apply these commands, changes, and settings to each Ethernet interface (for example: eth1, eth2). Disable Generic Receive Offload The Generic Receive Offload (GRO) feature, implemented by some Linux network drivers, causes poor read performance results. This feature can be disabled (turned off) using the ethtool utility. # ethtool ethX -K gro off Enable Flow Control Flow control is often negotiated properly, but a network that supports full flow control (RX and TX pause names on) is recommended. If your network infrastructure is set up to support flow control, you could benefit from forcing flow control to be on. The HIT/Linux eqltune utility recommends this change, but does not automatically implement it. # ethtool --pause ethX autoneg off rx on tx on To make this change persistent across reboots, add the command to the /etc/rc.local directory. Enable Jumbo Frames If supported by your networking infrastructure, enabling jumbo frames (that is, an MTU of 9000) enhances iSCSI throughput under heavy loads. The HIT/Linux eqltune utility recommends this change, but does not automatically implement it. In /etc/sysconfig/networking/devices/ifcfg-ethX, add this line: MTU=9000 Avoid ARP Flux The default value of 0 (zero) allows NICs to reply to ARP requests on any other NIC, which can result in false positives to externally originating ping tests, as well as unexpected ARP resets. This condition is known as ARP Flux. To avoid ARP Flux in a configuration with multiple NICs per subnet, apply the following parameters in /etc/sysctl.conf: net.ipv4.conf.ethX.arp_ignore = 1 net.ipv4.conf.ethX.arp_announce = 2 Loosen IPv4 Reverse Path Filtering To allow multiple iSCSI connections in a configuration with multiple NICs per subnet, reverse path filtering must be loosened. To loosen the filtering, use the following setting: net.ipv4.conf.ethX.rp_filter=2 NOTE: This setting is required only on RHEL version 6 and version 7 and on newer ubuntu and debian kernels. Configure Your Linux Operating System 21

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which can place a resource burden on both the EqualLogic arrays and the Linux host. Dell recommends that you change
the setting to manual. The HIT/Linux eqltune utility recommends this change, but does not automatically implement it.
node.startup = manual
Configure Linux Networking
Dell recommends that you configure multipathing for Ethernet interfaces on a Linux host to connect to an EqualLogic
group.
This configuration of multiple NICs per subnet requires that several Linux networking parameters be modified from their
default values for reliable implementation. The HIT/Linux eqltune utility, when run in fix mode, will automatically
configure the Linux operating system to operate correctly with this configuration.
NOTE: Apply these commands, changes, and settings to each Ethernet interface (for example: eth1, eth2).
Disable Generic Receive Offload
The Generic Receive Offload (GRO) feature, implemented by some Linux network drivers, causes poor read performance
results. This feature can be disabled (turned off) using the ethtool utility.
# ethtool ethX -K gro off
Enable Flow Control
Flow control is often negotiated properly, but a network that supports full flow control (RX and TX pause names
on
) is
recommended. If your network infrastructure is set up to support flow control, you could benefit from forcing flow
control to be on. The HIT/Linux eqltune utility recommends this change, but does not automatically implement it.
# ethtool --pause ethX autoneg off rx on tx on
To make this change persistent across reboots, add the command to the
/etc/rc.local
directory.
Enable Jumbo Frames
If supported by your networking infrastructure, enabling jumbo frames (that is, an MTU of 9000) enhances iSCSI
throughput under heavy loads. The HIT/Linux eqltune utility recommends this change, but does not automatically
implement it.
In
/etc/sysconfig/networking/devices/ifcfg-ethX
, add this line:
MTU=9000
Avoid ARP Flux
The default value of 0 (zero) allows NICs to reply to ARP requests on any other NIC, which can result in false positives to
externally originating ping tests, as well as unexpected ARP resets. This condition is known as ARP Flux. To avoid ARP
Flux in a configuration with multiple NICs per subnet, apply the following parameters in
/etc/sysctl.conf
:
net.ipv4.conf.ethX.arp_ignore = 1
net.ipv4.conf.ethX.arp_announce = 2
Loosen IPv4 Reverse Path Filtering
To allow multiple iSCSI connections in a configuration with multiple NICs per subnet, reverse path filtering must be
loosened. To loosen the filtering, use the following setting:
net.ipv4.conf.ethX.rp_filter=2
NOTE: This setting is required only on RHEL version 6 and version 7 and on newer ubuntu and debian kernels.
Configure Your Linux Operating System
21