Completed December 2011
Aim
The aim was to create a high performance iSCSI network and a fast link to our ESX hosts for a Veeam Backup & Replication job running overnight.
Background
Veeam is a product designed for the backup of VMware virtual machines in their entirety whilst being application aware and implementing advancing compression routines. The Local Area Network utilises two Dell PowerConnect 6248 L3 switches in a stack whilst the iSCSI setup uses PowerConnect 7024 switches. These switches are very capable providing configuration via browser basedGraphical User Interface or CLI. Being from a networking background the only real option here is to use the CLI. Anybody used to the Cisco IOS will feel right at home using the Dell PowerConnect CLI with only slight syntax differences evident.
Method
Firstly a fast network connection from our Veeam/ vCentre server to two ESX hosts was required. Having a quad port gigabit NIC installed on our vCentre meant that NIC teaming was possible, this allows two or more physical NICs to be teamed together to form an aggregate link. In my example, this was setup very quickly from the included HP application. The switch ports also required link aggregation configuration on our LAN. The port aggregation itself uses IEEE 802.3ad Link Aggregation Control Protocol to negotiate the port channel and provide failure detection. Once the port channel was configured on the switch the server soon registered the new 2Gbps aggregated links – job done!
The switch configuration is the same with the iSCSI as it was with the LAN connection. The only problem I have come across is that the iSCSI initiator in Windows Server 2008 does not save the connection configuration following a reboot. The only way to manage your connections is to take the iSCSI drive offline, logoff the session, logon the session with the correct connections and then reconfigure any fail-over routes. The difference with the iSCSI configurations is of course that your storage device also needs configuring with teamed LACP negotiated ports.
To optimise this setup ensure enough bandwidth is available from your vSwitches in VMWare for any backups. Also ensure jumbo frames (MTU 9216 on PC6248 & PC7024) and flow control are enabled on your switch infrastructure. Don’t forget spanning tree port fast (state forward on port activation) on your port channels and credentials on your VMware infrastructure for Veeam. My configuration also incorporated fail over paths over multiple stacked switches for both VMware and iSCSI, providing a degree of resiliency.
Results
Backup speeds increased by 5MBPs (That’s bytes NOT bits!!) and remote availability to our vCentre server is much more reliable.