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Required Adapter and Server OS Settings
113 Dell EMC Storage Compatibility Matrix for SC, PS, and FS Series Arrays | DSCM
Enable RFC1323 Timestamps
Enable RFC1323 timestamps (TCP High Performance Extensions) to prevent sequence number wrap under
high load, known as Prevention Against Wrapped Sequence (PAWS). High-load iSCSI connections are prone
to this issue, particularly at 10GbE or higher. Run this command at elevated CMD prompt to add a registry
key (set to value of 2 by default; this is the desired value):
netsh int tcp set global timestamps=enabled
The registry setting can be checked and confirmed as shown below:
• HKLM\SYSTEM\CurrentControlSet\Services\TCPIP\Parameters\Tcp1323Opts
• Values: 0 = Timestamps + windows scaling disabled
1 = Windows Scaling Enabled
2 = Timestamps enabled ✓
3 = both enabled
Disable Nagle’s Algorithm
To disable delayed ACK and Nagle’s algorithm, create the following DWORD 32-bit entries for each SAN
interface subkey in the Windows Server registry:
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<SAN
interface GUID>
Create or verify these DWORD 32-bit entries. Set them to a value of 1 (disabled)
TcpAckFrequency
TcpNoDelay
Disable NIC Interrupt Modulation:
1. Click Adapter Settings.
1. Right-click the adapter and select Properties.
2. Under the Networking tab, click Configure.
3. Under the Advanced tab, select Interrupt Moderation and choose Disabled.
Note: A reboot is required for any registry changes to take effect. Alternatively, unloading and reloading the
initiator driver will also cause the change to take effect. In the Device Manager GUI, under Storage
controllers, right-click Microsoft iSCSI Initiator, and select Disable to unload the driver. Then, select
Enable to reload the driver.