It's mostly about bandwidth. With VLANs, the public and cluster networks are going to be sharing the inter-switch links.
For a cluster that size, I don't see much advantage to the VLANs. You'll save a few ports by having the inter-switch links shared, at the expense of contention on those links.
If you're trying to save ports, I'd go with a single network. Adding a cluster network later is relatively straight forward. Just monitor the bandwidth on the inter-switch links, and plan to expand when you saturate those links.
That said, I am using VLANs, but my cluster is much smaller. I only have 5 nodes and a single switch. I'm planning to transition to a dedicated cluster switch when I need the extra ports. I don't anticipate the transition being difficult. I'll continue to use the same VLAN on the dedicated switch, just to make the migration less complicated.
On Tue, Nov 25, 2014 at 3:11 AM, Sreenath BH <bhsreenath@xxxxxxxxx> wrote:
Hi
For a large network (say 100 servers and 2500 disks), are there any
strong advantages to using separate switch and physical network
instead of VLAN?
Also, how difficult it would be to switch from a VLAN to using
separate switches later?
-Sreenath
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