VMware over ISCSI storage - Equal Logic

Recently there had been strong grow and push for the 2nd tier ISCSI storages from the SAN Storage company like Netapps, EMC, DELL, HP, IBM and etc. A lot of the white paper and marketing brochure had been publish and been communicated to the public in worldwide, which claim the VM is out perform with the ISCSI VS Fiber Channel SAN.

I would like to share couple of my finding in the real Prove of concept and test that myself had personally setup and experience here. VMware do support hardware base ISCSI HBA and software base ISCSI through its VMkernel. Couple of thing that you may want to consider before we really decide to proceed further with the ISCSI. Networking become more and more important since the last decade to be operate most of the important pieces in the Production Data Center. Networking had also become the major issue for most of the time especially in VM environment which may need a bigger bandwidth to support the multiple VMs that been consolidated to single Physical Host.

I had been invited by the Equal Logic vendor to run the real test with the demo in my datacenter. Below is the major finding I would want to share

Test Equipment
Server - DELL PE 2950 8GB and 2 x Quad Core 2.0 Ghz
Storage Switches - DELL Gigabit Switches
Storages - Equal Logic PS 5000 with SAS HDD
Operatin System - SUSE Linux, Windows 2003, ESX 3.5

Impressive

1. High Processing speed due to the processor build in for each storage bay. It can be scale up to 12 storage bay in the cluster basis. Each enclosure contains 16 physical spindle drives with SAS technology
2. Simplify management - the entire process to configure the storage to be useable is less than 15 Mins. Its all web base and able to run on the open source browser such as firefox
3. Maximize through put through the software ISCSI initiator been tested on servers and my personal laptop. It able to suck up 97% of the gigabit through put from my laptop gigabit connection and the server gigabit connection as well.
4. High redundancy with global hotspare configuration recommended
5. Impressive load balance feature which able to scale from storage and perfomance perspective. Additional enclosure will provide additional spindle power and processing power from the stroage bay. Compare to Clariion series currently, which always provide slow perfomance when the storage are only 60% populated.
6. Shorter commissioning process and reduce provisioning time line. almost plug and play
7. RAID 50 available as an option to be configure during the provision process
   

Disadvantages

1. Now is time to think about long term strategy in Data Center before it become another mess as old days which we manage the Fiber Channel without director switch with fabric port. In order to gain the perfomance and scalability, each of the network connection, uplink and downstream will direct impact to the through put for each storage box. In Fiber Channel world, as if you run in 4Gb FC switches and cascaded, you will at least have 8Gb redundancy and load balance trough put from switch to switch perspective. In ethernet, we may have to look at 10Gbps uplink from switches perspective. Conclusion, the switch uplink will direct impact the entire storage throughput to the client
2. As you may start to manage the ISCSI with distributed or seperate from the normal ethernet in DC, this could generate extra workload from management perspective as well as support operational overhead
3. ISCSI over 10GbE are in roadmap but yet to be release, as the current gigabit ISCSI price seems to be little bit too high to be compareable with the fiber channel SAN.
   
4. Software ISCSI had higher overhead in the Server resources compare to FC HBA storage

Summary
My opinion here is to wait for the 10GbE release on the ISCSI before to really decide for ISCSI to replace the major FC SAN Storage for High Availability purpose. As for now, it may be suitable to be deploy in Disaster Recovery Solution, Development VM Farm and Unmanage location example factory, branch office which do not have the complete Data Center solution. This is specifically for solution related to ISCSI in VMware.