Announcing the Death of RAID
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RAID and RAIN have overlap in the two node world. But here is a quick breakdown of which makes the most sense where.
- Single Server: RAID
- Dual Server Cluster: Network RAID or RAIN
- Three or More Server Cluster: RAIN
It's the number of nodes in a related cluster (shared storage) that makes the difference. And RAIN may encourage systems that were not clustered before to become clustered, as well.
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RAIN can be scaled down to a single node, but you lose the "requirement" of nodal protection. So we could think of it as "RAIN 0" or a RAIN in a failed state. Examples of this include the single node Scale HC3 product and the single node Exablox implementation.
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@scottalanmiller said in Announcing the Death of RAID:
RAIN can be scaled down to a single node, but you lose the "requirement" of nodal protection. So we could think of it as "RAIN 0" or a RAIN in a failed state. Examples of this include the single node Scale HC3 product and the single node Exablox implementation.
Right... but ideally to convert a single node RAIN instance to a two-node RAIN cluster, you only need to add a second host and appropriate storage, right?
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@dafyre said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
RAIN can be scaled down to a single node, but you lose the "requirement" of nodal protection. So we could think of it as "RAIN 0" or a RAIN in a failed state. Examples of this include the single node Scale HC3 product and the single node Exablox implementation.
Right... but ideally to convert a single node RAIN instance to a two-node RAIN cluster, you only need to add a second host and appropriate storage, right?
Depends on if you are addressing the need for a witness node. In theory, yes two node can do RAIN. But it comes with complications.
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@scottalanmiller said in Announcing the Death of RAID:
@dafyre said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
RAIN can be scaled down to a single node, but you lose the "requirement" of nodal protection. So we could think of it as "RAIN 0" or a RAIN in a failed state. Examples of this include the single node Scale HC3 product and the single node Exablox implementation.
Right... but ideally to convert a single node RAIN instance to a two-node RAIN cluster, you only need to add a second host and appropriate storage, right?
Depends on if you are addressing the need for a witness node. In theory, yes two node can do RAIN. But it comes with complications.
OK considering the witness role, are you saying it's mostly wise to not worry about RAIN until you reach 3+ nodes?
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@Dashrender said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
@dafyre said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
RAIN can be scaled down to a single node, but you lose the "requirement" of nodal protection. So we could think of it as "RAIN 0" or a RAIN in a failed state. Examples of this include the single node Scale HC3 product and the single node Exablox implementation.
Right... but ideally to convert a single node RAIN instance to a two-node RAIN cluster, you only need to add a second host and appropriate storage, right?
Depends on if you are addressing the need for a witness node. In theory, yes two node can do RAIN. But it comes with complications.
OK considering the witness role, are you saying it's mostly wise to not worry about RAIN until you reach 3+ nodes?
Generally, yes. Nothing wrong with it at one node, just not very much value to it there. And at two nodes, no one is focused on making that work well, it's just niche and unimportant.
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@scottalanmiller said in Announcing the Death of RAID:
- Closed Source RAIN Software: AetherStore
It doesn't seem like you can use AetherStore for VM storage?
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@FATeknollogee said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
- Closed Source RAIN Software: AetherStore
It doesn't seem like you can use AetherStore for VM storage?
Hrm, is that a challenge? If it can be mounted on the hypervisor, it can be used as storage. Now I want to go test, and I just don't have the time!
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I just looked at the website use cases & it didn't mention anything about virtualization, so I assumed it couldn't be used.
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@FATeknollogee said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
- Closed Source RAIN Software: AetherStore
It doesn't seem like you can use AetherStore for VM storage?
You CAN, but you sure wouldn't.
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@travisdh1 said in Announcing the Death of RAID:
@FATeknollogee said in Announcing the Death of RAID:
@scottalanmiller said in Announcing the Death of RAID:
- Closed Source RAIN Software: AetherStore
It doesn't seem like you can use AetherStore for VM storage?
Hrm, is that a challenge? If it can be mounted on the hypervisor, it can be used as storage. Now I want to go test, and I just don't have the time!
It's a block device, it has to work. Would just be awful.
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@FATeknollogee said in Announcing the Death of RAID:
I just looked at the website use cases & it didn't mention anything about virtualization, so I assumed it couldn't be used.
Just not a good use case for it. It's a block device, which should tell you everything that you need to know. It can be used for any block device task - including building a SAN on top of it.
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@scottalanmiller
A SAN built on 5400-7200 rpm spindles(probably) of varying size/cache, over a network with all your other traffic on it.
Huge performance. -
@momurda said in Announcing the Death of RAID:
@scottalanmiller
A SAN built on 5400-7200 rpm spindles(probably) of varying size/cache, over a network with all your other traffic on it.
Huge performance.Not only that, the write speed of Aetherstore isn't fast enough to keep up with running VMs.
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@momurda said in Announcing the Death of RAID:
@scottalanmiller
A SAN built on 5400-7200 rpm spindles(probably) of varying size/cache, over a network with all your other traffic on it.
Huge performance.And it is not designed for speed, so even with a dedicated network and SSDs, it isn't all that fast. Not built for that.
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@scottalanmiller nice article
Something to add to the learnings for this year -
@scottalanmiller said in Announcing the Death of RAID:
@coliver said in Announcing the Death of RAID:
Is StarWinds vSAN considered RAIN?
We'd have to dig in under the hood. I think that they are mostly focused on network RAID, just really advanced.
StarWind uses local reconstruction codes (for now - stand-alone software or hardware RAID on every node; can be RAID0, 1, 5, 6 or 10) and inter-node n-way replication between the nodes, can be considered as a network RAID1. There's no network parity RAID like HPE (ex-Left Hand) or Ceph does.
P.S. We're working on our own local reconstruction codes now, so local protection (SimpliVity style) won't be required soon. FYI.
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...and then you have companies that cluster servers, with each server having RAID configured. Sacrificing some usable storage there.
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@BBigford said in Announcing the Death of RAID:
...and then you have companies that cluster servers, with each server having RAID configured. Sacrificing some usable storage there.
That's not uncommon and that's kinda of what Kooler is talking about, they use RAID often on individual nodes as a local means of avoiding full rebuilds under most conditions.
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I would treat RAID as a kind of hardware offload since RAIN is known to consume more resources and thus resulting in less performance from the storage array. That is probably one of the major reasons why vendors like StarWind keep using hardware RAID. Especially on smaller deployments (storage capacities).
