Infrastructure Needed for Hypervisor Cluster
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RAID's primary function is to protect against data loss, not availability loss. The latter is generally seen as a by product, not a goal. Data loss, for a normal business, has a massive cost and risk compared to availability. One hour of lost productivity is often trivial to absorb and can often even be made up. Losing one hour of customer information could result in pretty tragic loss of information. And RAID tends to protect against a lot of data loss, and a little uptime. Also, RAID costs starts around $100, and average is probably around $800 to implement. But protects against huge data loss in most cases.
Clustering does not protect against data loss (and can actually contribute to data loss if we aren't careful.) Clustering only (under normal conditions) protects against availability loss, the lesser factor with RAID. So we have to justify clustering based solely off of improved up time, not loss of data. That makes it much harder to justify and tips the scales from "always do it" to "almost never do it." The difference is that dramatic.
And the starting cost of clustering is generally several thousand dollars with the average likely being in the tens of thousands.
Also, RAID requires essentially zero IT skills. You can get it as simply as checking a box when ordering a server. Clustering, however, requires a lot of complex interactions, includes a bit of risk, and normally a huge amount of either cost or expertise or both.
So basically... RAID is a few hundred dollars to protect against some of the worst issues you can face, with zero overhead. Clustering costs tens of thousands to protect against something generally trivial with loads of overhead.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
Both node A and B would have enough power to be able to handle all of the deployed VMs. The thought behind this is when Node A need to be rebooted, you evacuate Node A's VMs to Node B. This line of thought would not address how to handle the sudden loss of Node A, unless Node A and B are somehow constantly in sync.
This is a fine way to look at it. Just remember that your capacity planning here is based on high availability, not on hyperconvergence. HC doesn't require you to provide that level of capacity, HA does. If you want HC + HA, then this is the right way to capacity plan.
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. You would then need software to manage the cluster. I assume this is where applications like oVirt or Failover Cluster Manager come into play. If true, then you'd have a VM running on one of the nodes whose purpose is to run the management application.
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Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?
Is it vSAN (or equivalent)?
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Maybe a dumb question
Hey now! Only I get to be t3h n00b in this thread
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?
Is it vSAN (or equivalent)?
Hyperconverged just means everything is in the same box: storage, compute, network... Vsan has nothing to do with the name.
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@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.
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?
Nothing, that's all hyperconverged is, assuming the local storage piece is shared. All the pieces together in a single layer, managed together.
Just like an IPOD is nothing more than the opposite
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@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Is it vSAN (or equivalent)?
That's the sharing mechanism, yeah. So a Starwind style vSAN, a Gluster style native sharing, a DRBD RAID, etc. Any of those.
A non-converged cluster would be where the only thing connecting them is the management layer.
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@Obsolesce said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?
Is it vSAN (or equivalent)?
Hyperconverged just means everything is in the same box: storage, compute, network... Vsan has nothing to do with the name.
If you have a single node, that's true. With more than one node, it needs the extra terminology of the storage and management being shared across hosts. And I think that you need the ability to migrate workloads (not HA, just the ability to move them.) That's so basic, no one mentions it.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@Obsolesce said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?
Is it vSAN (or equivalent)?
Hyperconverged just means everything is in the same box: storage, compute, network... Vsan has nothing to do with the name.
If you have a single node, that's true. With more than one node, it needs the extra terminology of the storage and management being shared across hosts. And I think that you need the ability to migrate workloads (not HA, just the ability to move them.) That's so basic, no one mentions it.
Storage is not "shared" as I understand it, hence the "shared nothing" in shared nothing architecture.
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@Obsolesce said in Infrastructure Needed for Hypervisor Cluster:
Storage is not "shared" as I understand it, hence the "shared nothing" in shared nothing architecture.
It is totally shared, has to be. All nodes see all storage. It's not "codependent."
HC isn't "shared nothing".
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
HC isn't "shared nothing".
Never said it was. I was implying that a big use case of vSAN has been in a shared nothing architecture.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
That's what I'm having a hard time wrapping my head around: Making shared storage available without the IPOD.
IPOD isn't the natural way to have shared storage. In your mind, as many people do because of marketing, the idea that storage is consolidated and external is just assumed, and that naturally leads you to an IPOD. Stop trying to consolidate and externalize as part of your sharing, and magically you go to hyperconvergence.
Every standalone server in the world is hyperconverged. . .
Compute and storage all in 1 box.
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@Obsolesce said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
HC isn't "shared nothing".
Never said it was. I was implying that a big use case of vSAN has been in a shared nothing architecture.
vSAN's only real purpose is for sharing. "Shared" is being used two different ways here.
The components aren't shared, the resulting workload is shared.
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@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
That's what I'm having a hard time wrapping my head around: Making shared storage available without the IPOD.
IPOD isn't the natural way to have shared storage. In your mind, as many people do because of marketing, the idea that storage is consolidated and external is just assumed, and that naturally leads you to an IPOD. Stop trying to consolidate and externalize as part of your sharing, and magically you go to hyperconvergence.
Every standalone server in the world is hyperconverged. . .
Compute and storage all in 1 box.
That's absolutely correct, understanding that is key to understanding hyperconvergence. It is that aspect that makes HC so powerful. It also helps people to understand why standalone servers are more reliable than IPODs that cost 600% more.
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@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
@EddieJennings said in Infrastructure Needed for Hypervisor Cluster:
That's what I'm having a hard time wrapping my head around: Making shared storage available without the IPOD.
IPOD isn't the natural way to have shared storage. In your mind, as many people do because of marketing, the idea that storage is consolidated and external is just assumed, and that naturally leads you to an IPOD. Stop trying to consolidate and externalize as part of your sharing, and magically you go to hyperconvergence.
Every standalone server in the world is hyperconverged. . .
Compute and storage all in 1 box.
Exactly. So back to my original comment in that VSAN has nothing to do with HC...
@Obsolesce said in Infrastructure Needed for Hypervisor Cluster:
@Pete-S said in Infrastructure Needed for Hypervisor Cluster:
Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?
Is it vSAN (or equivalent)?
Hyperconverged just means everything is in the same box: storage, compute, network... Vsan has nothing to do with the name.
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To better explain hyper-convergence, think of it like this.
You take several smaller boxes and create a virtual, larger box out of the individual smaller boxes.
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@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:
3PAR makes it less likely to be redundant, rather than more, I would wager.
3PAR is Active/active symmetric architecture with a full fiber mesh between controllers. Most cases where I've seen issues were tied to firmware on SSD's (Specifically the ~4TB Samsung ones) and people making giant RAID 5 pools, or people trying to move the array while it's running (yes this is dumb).
One really nice thing with the array is it does offer pretty solid vVols support with vSphere so you can manage it as a object system in that regards (No need for VMFS).
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@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
You take several smaller boxes and create a virtual, larger box out of the individual smaller boxes.
When you say that I think of LPAR combining servers (Bull, Hitachi).
HCI is just about doing for networking and storage what virtualization has already done for computing. -
@StorageNinja said in Infrastructure Needed for Hypervisor Cluster:
@DustinB3403 said in Infrastructure Needed for Hypervisor Cluster:
You take several smaller boxes and create a virtual, larger box out of the individual smaller boxes.
When you say that I think of LPAR combining servers (Bull, Hitachi).
HCI is just about doing for networking and storage what virtualization has already done for computing.That is the goal, do the same thing that virtualization has, but across more boxes with networking.
That's the most simplistic way to explain HCI to laymen.
