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I certainly think that NAS access has its place in the VMWare world, but if you have a large data center that already has an investment in FC, I would really suggest using it for your ESX host connections. A few reasons, which I will discuss below:
1GB vs 2GB. Although this is not really an issue for almost all Windows hosts, remember what VMWare does. Your going to be running many (lets guess 10 for right now) Windows machines down that one trunk. So, each machine has about 100Mb/200Mb of effective throughput. This is almost never an issue, execept when you start to pull backups. When you pull backups, your going to be hitting all the VMs hard for IO, you will see a difference between NAS and FC.
IO offload. FC cards are HBA's, they offload much of the storage processing. This is significant in the VMWare world; I went (on the same servers) from local to FC SAN disk, and the system processor (host system) dropped 20%, just by offloading the IO from the processor. You can use TOE, but it does not offload as much as an HBA.
Reliability. FC is tried and true in the VMWare world.
Cost? FC is very expensive, there is no denying that. However, think about what your doing; your jamming 10 servers down 1 FC card. When you amortize that cost over the VMs, the $$$ spent for the FC adapter really becomes a non-issue (figure 2000 for 2 single port adapters, or 200/server for disk connectivity; not bad).
Someone mentioned using SAN snapshots using NetApp; you can do this using NFS/iSCSI/FC. It does not matter. It works a little different for each, but there is not really any difference between any of them (NetApp stores the FC LUNs as a file, when you take a Snap, your actually taking a Snap of the .LUN file. In the VMWare world, this is exactly the same as taking a Snap of the VMDK file).
FC adds complexity; and costs significant $$$. However, if you have the infrastructure already, I would suggest that you connect the servers via FC. If your looking to build a large VMware farm in the future; again FC presents the right option. However, for many people NAS is the way to go.
Its great that we have all the options; they all have their place. However, nothing out today is gong to top FC for speed. Unfortunately, nothing is gong to top it for cost or complexity either.
1GB vs 2GB. Although this is not really an issue for almost all Windows hosts, remember what VMWare does. Your going to be running many (lets guess 10 for right now) Windows machines down that one trunk. So, each machine has about 100Mb/200Mb of effective throughput. This is almost never an issue, execept when you start to pull backups. When you pull backups, your going to be hitting all the VMs hard for IO, you will see a difference between NAS and FC.
IO offload. FC cards are HBA's, they offload much of the storage processing. This is significant in the VMWare world; I went (on the same servers) from local to FC SAN disk, and the system processor (host system) dropped 20%, just by offloading the IO from the processor. You can use TOE, but it does not offload as much as an HBA.
Reliability. FC is tried and true in the VMWare world.
Cost? FC is very expensive, there is no denying that. However, think about what your doing; your jamming 10 servers down 1 FC card. When you amortize that cost over the VMs, the $$$ spent for the FC adapter really becomes a non-issue (figure 2000 for 2 single port adapters, or 200/server for disk connectivity; not bad).
Someone mentioned using SAN snapshots using NetApp; you can do this using NFS/iSCSI/FC. It does not matter. It works a little different for each, but there is not really any difference between any of them (NetApp stores the FC LUNs as a file, when you take a Snap, your actually taking a Snap of the .LUN file. In the VMWare world, this is exactly the same as taking a Snap of the VMDK file).
FC adds complexity; and costs significant $$$. However, if you have the infrastructure already, I would suggest that you connect the servers via FC. If your looking to build a large VMware farm in the future; again FC presents the right option. However, for many people NAS is the way to go.
Its great that we have all the options; they all have their place. However, nothing out today is gong to top FC for speed. Unfortunately, nothing is gong to top it for cost or complexity either.
What do you think about this comparative SAN and iSCSI on FAS3020 ?
Network Appliance FAS3020 and EMC CX500: Comparison of Usability and Performance
PS : Don't see EMC CX500 graph
Message was edited by:
ken.cline@hp.com to shorten URL
Network Appliance FAS3020 and EMC CX500: Comparison of Usability and Performance
PS : Don't see EMC CX500 graph
Message was edited by:
ken.cline@hp.com to shorten URL
