Setup Guide

Summary of Recommended Changes
Table 5. Summary of Recommended Changes summarizes the changes to Linux settings that are recommended by Dell.
Table 5. Summary of Recommended Changes
Area Setting Default Value Recommended Value
(EQL)
SCSI block devices Device timeout 30 seconds 60 seconds
Per SCSI device read-ahead buffer 128KB 1024KB
Per SCSI device I/O scheduler CFQ noop
iSCSI settings node.session.iscsi.FastAbort Yes No
iSCSI settings node.startup automatic manual
Ethernet devices Generic Receive Offload on off
Ethernet devices
1
flow control
1
auto-negotiate on
Ethernet devices
1
jumbo frames
1
(MTU size) 1500 9000
Sysctl tunable - ARP net.ipv4.conf.ethX.arp_ignore 0 1
Sysctl tunable - ARP net.ipv4.conf.ethX.arp_announce 0 2
Sysctl tunable - ARP
2
net.ipv4.conf.ethX.arp_filter 0 2
1
Verify that the network infrastructure supports these two settings (flow control and jumbo frames) before implementing
them. To enable pause auto-negotiation, use the ethtool –pause ethX autoneg off command.
2
This setting is required only on RHEL version 6 and version 7 and on newer ubuntu and debian kernels.
Table 6. Optional Changes lists other changes to Linux settings that Dell suggests should be applied to /etc/sysctl.conf.
Table 6. Optional Changes
Area Setting Recommended Value (EQL)
Sysctl tunable net.core.rmem_max 16777216
Sysctl tunable net.core.wmem_max 16777216
Sysctl tunable net.ipv4.tcp_rmem 8192 87380 16777216
Sysctl tunable net.ipv4.tcp_wmem 4096 65536 16777216
Sysctl tunable net.core.wmem_default 262144
Sysctl tunable net.core.rmem_default 262144
iSCSI settings node.sessions.cmd_max 1024
iSCSI settings node.session.queue_depth 128
iSCSI settings iscsi.MaxRecvDataSegmentLength 131072
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Configure Your Linux Operating System