Infrastructure Needed for Hypervisor Cluster
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@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
So if HA isn't necessary, you could potentially have nodes with various hardware -- such as in my lab where I've accumulated two different servers with different hardware specs: a Dell R310 and a Dell T420.
Sure. People do that all of the time.
Excellent. So back in my lab with two dissimilar servers, I'd have the same hypervisor on each, then one of them would have a VM running the application used to create and manage the cluster. Example applications would be oVirt if I'm wanting to use KVM on the nodes, or perhaps Failover Cluster Manager if I wanted to use Hyper-V on the nodes..
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Maybe try to find a used multi-node server. Many manufacturers makes them - Dell, HPE, Fujitsu, IBM, Supermicro, Intel etc. They're not blade servers, more often 2U servers with 2 or 4 motherboards inside. I guess you could for blade servers too. Search for node server and you'll find them.
PS. I see you have Dell servers. In the Dell world it's the PowerEdge C series servers that are their multinode machines.
I'd love to have more, but two is what I have. I think for my initial goal of just learning to build a cluster of greater than 1 server can still be achieved.
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
But I guess you could even do it with just one server and use nested virtualization. The question is how realistic its going to be compared to a real cluster. But maybe it will be enough.
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If you wanted to purchase cheap servers (excluding xByte as they are more for production in terms of cost and warranty) you might get more bang for your buck from a vendor like OrangeComputers.com
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
But I guess you could even do it with just one server and use nested virtualization. The question is how realistic its going to be compared to a real cluster. But maybe it will be enough.
Yeah. I'm not interested in trying to pull off nested virtualization, since like you say, it's not something that I'll deal with in the real world.
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@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
But I guess you could even do it with just one server and use nested virtualization. The question is how realistic its going to be compared to a real cluster. But maybe it will be enough.
Yeah. I'm not interested in trying to pull off nested virtualization, since like you say, it's not something that I'll deal with in the real world.
Pick a Hypervisor and add StarWind VSAN to both nodes. You get your shared storage that way and for a lab environment, that should be perfect.
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@dafyre said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
But I guess you could even do it with just one server and use nested virtualization. The question is how realistic its going to be compared to a real cluster. But maybe it will be enough.
Yeah. I'm not interested in trying to pull off nested virtualization, since like you say, it's not something that I'll deal with in the real world.
Pick a Hypervisor and add StarWind VSAN to both nodes, and make sure both nodes have enough room for holding all the VMs... You get your shared storage that way and for a lab environment, that should be perfect.
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Not only is it enough, it's often recommended. There is no such requirement of needing three servers.
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
That's a VMware requirement, not a clustering requirement. And even on VMware, it's not an actual requirement, they just need a third witness that isn't part of the cluster.
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@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
But I guess you could even do it with just one server and use nested virtualization. The question is how realistic its going to be compared to a real cluster. But maybe it will be enough.
Yeah. I'm not interested in trying to pull off nested virtualization, since like you say, it's not something that I'll deal with in the real world.
Nothing like that needed, two node clusters are the standard for the SMB. Three and larger is for scalable clusters (where you can grow by just adding a node.)
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
That's a VMware requirement, not a clustering requirement. And even on VMware, it's not an actual requirement, they just need a third witness that isn't part of the cluster.
But what most people do is put that Witness on their 2-node cluster. . . .
Which could cause issues for all kinds of reasons. .
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@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
That's a VMware requirement, not a clustering requirement. And even on VMware, it's not an actual requirement, they just need a third witness that isn't part of the cluster.
But what most people do is put that Witness on their 2-node cluster. . . .
Which could cause issues for all kinds of reasons. .
Yeah, but no need for the witness node outside of VMware.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
That's a VMware requirement, not a clustering requirement. And even on VMware, it's not an actual requirement, they just need a third witness that isn't part of the cluster.
But what most people do is put that Witness on their 2-node cluster. . . .
Which could cause issues for all kinds of reasons. .
Yeah, but no need for the witness node outside of VMware.
I think you mean, no need for a 3rd ESXi VMWare box just to run the node.
It is recommended to be outside of the cluster, but they specifically say it does work if you wanted it on the cluster. (with a crap ton of asterisks following the statement)
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@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
When I looked at it I came to the conclusion that I would need a minimum of three nodes and they should be the same CPU generation and have the same NIC configuration.
That's a VMware requirement, not a clustering requirement. And even on VMware, it's not an actual requirement, they just need a third witness that isn't part of the cluster.
But what most people do is put that Witness on their 2-node cluster. . . .
Which could cause issues for all kinds of reasons. .
Yeah, but no need for the witness node outside of VMware.
I think you mean, no need for a 3rd ESXi VMWare box just to run the node.
It is recommended to be outside of the cluster, but they specifically say it does work if you wanted it on the cluster. (with a crap ton of asterisks following the statement)
Correct, can be on a desktop or whatever.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Not only is it enough, it's often recommended. There is no such requirement of needing three servers.
Xenserver recommends three (or more) for HA.
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Not only is it enough, it's often recommended. There is no such requirement of needing three servers.
Xenserver recommends three (or more) for HA.
Everyone recommends 3 or more hosts.
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@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Not only is it enough, it's often recommended. There is no such requirement of needing three servers.
Xenserver recommends three (or more) for HA.
Everyone recommends 3 or more hosts.
Not everyone. Starwinds does not, for example.
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Not only is it enough, it's often recommended. There is no such requirement of needing three servers.
Xenserver recommends three (or more) for HA.
XS is one specific vendor that sells licenses. So they have a financial incentive to push the 3+ host model. And their standard shared storage mechanism only works well with 3+. So they chose a system based around that, so that they recommend it is expected.
But products like DRBD and Starwind are engineered all around the 2 node model. They scale up, but their intent is focused on two nodes.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
XS is one specific vendor that sells licenses. So they have a financial incentive to push the 3+ host model. And their standard shared storage mechanism only works well with 3+. So they chose a system based around that, so that they recommend it is expected.
But products like DRBD and Starwind are engineered all around the 2 node model. They scale up, but their intent is focused on two nodes.
HPE Simplivity works normally with 2 nodes so does Datacore's VSAN. Although both require/should have a witness. I was looking into Simplicity to run a vSphere cluster some time ago but after HPE had bought them their support hit rock bottom at some stage. DataCore is a bit of a dark sheep, I wonder if anyone on ML ever used them at all. I'd look at Starwind and VMware VSANs first, both have large vendor and IT community support. Unless the OP wants to do some KVM with DRBD, Gluster, Ceph etc.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
Clustering is done when the cost of clustering is low versus the risk of not clustering.
I would change that slightly to Clustering is done when the cost of clustering is low versus the cost of not clustering. A risk is always a cost, but some costs are not risks. For example taking down a hypervisor for maintenance vs moving guests to another node and taking down a free node for maintenance.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
I don't think two nodes is enough if you want to play with clusters. Better to have more nodes with less ram/cpu and storage. Like 4 or 6 or something.
Not only is it enough, it's often recommended. There is no such requirement of needing three servers.
Xenserver recommends three (or more) for HA.
Everyone recommends 3 or more hosts.
Not everyone. Starwinds does not, for example.
fair enough
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@Vlinderbeest said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
Clustering is done when the cost of clustering is low versus the risk of not clustering.
I would change that slightly to Clustering is done when the cost of clustering is low versus the cost of not clustering. A risk is always a cost, but some costs are not risks. For example taking down a hypervisor for maintenance vs moving guests to another node and taking down a free node for maintenance.
Sure, using risk cost vs investment cost as cost v cost is a perfect valid way to look at it. I use that all the time in the opposite way.
You can say that risk is a cost. Or conversely, you can look at the clustering cost up front as essentially a "financial event" similar to an outage.
