Jumbo Frames and iSCSI Optimization for Compellent

Due to the performance issues with the SAN connectivity to to the server via iSCSI, some changes need to be made to the network to try to improve this.

Here are the changes that have already been made:

- Compellent Copilot (Support), have increased cache read blocks from 64 to 128. they are able to increase that to 256 if need be. This option is not available for us to change with this release of the software (version 4.1.4, but this becomes a dynamic change based on the type of data being written and read (Database, Files, etc …, in version 4.2.2).

This version is available for us to upgrade to. However, we will need to have them do a pre-check on our system to make that update available for download. The upgrade would take about 45 minutes, and would need to disconnect the hosts from the SAN to perform it.

- Also disabled Spanning Tree on the 3Com 4200 iSCSI switch, as this is a best practice known to improve iSCSI performance.

The following change still need to be made as well:

1- Toggle Jumbo Frames on Compellent on iSCSI1 and iSCSI2
2- Turn on Jumbo Frames on VLAN 200 ports on 3Com 4200G iSCSI Switch, and set them to 9000
3- Nail down iSCSI ports on 3Com 4200G switch to 1000/Full
4- Nail down Physical iSCSI NIC on VMHost7 to 1000/Full

- NIC Properties --> Network Adapters tab --> Edit --> 1000Mbit/Full Duplex

5- Turn on Jumbo Frames MTU 9000 on VMHost7
(Following need to be done from an SSH console to VMHost7)
- Delete Existing VMKernel PortGroup

esxcfg-vswitch.pl -D "VMKernel" iSCSI

- Create a the iSCSI Portgroup

esxcfg-vswitch.pl -A "IP Storage" iSCSI

- Create the new VMKernel NIC and give it an IP with the correct MTU (9000)

esxcfg-vmknic -a -i 192.168.200.7 -n 255.255.255.0 -m 9000 IPStorage

6- Turn on Jumbo Frames vSwitch on VMHost7 MTU 9000

esxcfg-vswitch -m 9000 vSwitch1

(check that the change took effect with:
esxcfg-vswitch -l)

8- Turn on Jumbo Frames MTU 9000 on Postal
- Go to Adapter configuration and change MTU from 1500 to 9000

9- Turn on Jumbo Frames MTU 9000 on Mimosa
- Go to Adapter configuration and change MTU from 1500 to 9000

10- Nail down iSCSI NIC to 1000/Full on do-mimosa
- Go to adapter configuration and change Duplex from auto to 1Gb Full Auto

11- Turn on Jumbo Frames MTU 9000 on Mimosa SQL
- Go to adapter configuration and change Jumbo MTU from 1500 to 9000

12- Nail down iSCSI NIC to 1000/Full on do-mimosa-sql
- Go to adapter configuration and change Duplex from auto to 1Gb Full Auto

• These changes were made on 03/18/2008 @ 2:00 pm
• All changes have worked as expected, except for the Jumbo Frames on the Exchange server (Postal) – VM – Which seems to still be communicating at 1500MTU. Richard will be rebooting Exchange tonight to see if this will make a difference.