Xenserver and Storage
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@jrc said in Xenserver and Storage:
So currently I have 2 HP servers that are being used and XenServer hosts.
It is kind of the objective from what I am seeing. It may not be THE objective, but other solutions require buying an unnecessary extra server just to have a third, so that's a pretty big negative.
Changing from Xen to KVM or Hyper-V is free and generally trivial. Adding 50% hardware overhead to make XenServer work is not. So take any reaction you had to moving off of Xen and magnify that by a few orders of magnitude for the equivalent reaction to adding more hardware to fix Xen-ecosystem shortcomings.
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@olivier said in Xenserver and Storage:
@scottalanmiller said in Xenserver and Storage:
@olivier said in Xenserver and Storage:
And in short, because Starwind doesn't support XenServer, you think it's better to discard XenServer
Why not, maybe in 2 nodes scenario it's an acceptable point of view ^^What's the other option? HA-Lizard is only available for two nodes. Nothing else is on the market. Starwind, like everyone else, is expected to have something out for Xen in the future, but no one seems to have solutions today. DRBD does work, but isn't ideal and XenServer specifically disavows it. Leaving a weird situation where we can come up with solutions, but we lack elegance or support. When switching out Xen seems to be the obvious solution making all of this moot.
2 node isn't the objective? So why discard that option?
Not discarded, just... absurd?
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I don't see the logical connection. Right now, he owns 2 hosts, XS can work with HA lizard or XOSAN in few weeks. No need to buy extra hardware. That's an option. Not maybe a perfect option, but it's not an absurd one.
I don't understand why you are speaking about a 50% hardware overhead to make XenServer work.
I didn't know about the potential 2 nodes capability of StarWind (I still need to understand how
), so the only absurd thing is to make me tell stuff I never said 
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I didn't know about the potential 2 nodes capability of StarWind (I still need to understand how
)Me too! (Again Not rethoric)
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@olivier said in Xenserver and Storage:
I didn't know about the potential 2 nodes capability of StarWind (I still need to understand how
), so the only absurd thing is to make me tell stuff I never said You asked why adding extra nodes wasn't an option. So I answered.
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@olivier said in Xenserver and Storage:
I don't see the logical connection. Right now, he owns 2 hosts, XS can work with HA lizard or XOSAN in few weeks. No need to buy extra hardware. That's an option. Not maybe a perfect option, but it's not an absurd one.
Right, and we covered, a few times I thought, that HA-Lizard really isn't up to snuff and not all that viable. So we can't keep repeating that as an excuse for things working.
XOSAN we can evaluate when it is on the market and tested.
So again, at this time, didn't we just come back to "no solutions today on Xen"?
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@scottalanmiller said in Xenserver and Storage:
@olivier said in Xenserver and Storage:
I didn't know about the potential 2 nodes capability of StarWind (I still need to understand how
), so the only absurd thing is to make me tell stuff I never said You asked why adding extra nodes wasn't an option. So I answered.
No, maybe I wasn't clear (EN not my main language).
You said: HA Lizard is only available for 2 nodes.
I answered that's exactly what he wanted (2 nodes) so why discarding HA lizard? -
@scottalanmiller said in Xenserver and Storage:
@olivier said in Xenserver and Storage:
I don't see the logical connection. Right now, he owns 2 hosts, XS can work with HA lizard or XOSAN in few weeks. No need to buy extra hardware. That's an option. Not maybe a perfect option, but it's not an absurd one.
Right, and we covered, a few times I thought, that HA-Lizard really isn't up to snuff and not all that viable. So we can't keep repeating that as an excuse for things working.
XOSAN we can evaluate when it is on the market and tested.
So again, at this time, didn't we just come back to "no solutions today on Xen"?
I personally don't like solutions that doesn't scale, but if he want to stick on 2 hosts, that's an option. People said it works when it's backed with support. I never heard nor bad or good stories about it. So I wouldn't discard it just after one or two people saying something here. Maybe you have a better knowledge on HA Lizard community and feedback of users? I don't.
Regarding XOSAN, it's already available to test since 6 months and commercial release is in just weeks.
I just said you are really prompt to discard options but again I can be mistaken because I don't have the deep knowledge on HA Lizard community. And again, I wasn't aware of 2 node capability of Starwind.
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@olivier said in Xenserver and Storage:
I personally don't like solutions that doesn't scale,
Me too, one of the reasons that I like Starwind is that it is amongst the largest scaling solutions on the market. It is limited by the hypervisor limits, not its own.
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@olivier said in Xenserver and Storage:
I just said you are really prompt to discard options but again I can be mistaken because I don't have the deep knowledge on HA Lizard community. And again, I wasn't aware of 2 node capability of Starwind.
It's not me discarding HA-Lizard. The community has worked with it a bit and as a community, the general consensus has been that it just isn't stable enough to use (and doesn't scale.) I'm just repeating a concensus to you. If you feel I'm dismissing things out of hand, it is the community, not me, that you are speaking to. I'm just explaining to you why it is viewed that way.
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That's why I asked if you have better knowledge of community on this solution because I really don't. So if it's the case, that it's not stable (darn, it's here since a long time!), that's indeed not an option.
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@olivier said in Xenserver and Storage:
That's why I asked if you have better knowledge of community on this solution because I really don't. So if it's the case, that it's not stable (darn, it's here since a long time!), that's indeed not an option.
I only know what people have been seeing. Part of the inherent downside to it is that it is specifically "forbidden" by XenServer as it is DRBD. So while it is fine to do, you have to accept that you are going against the closest thing that XS has to a primary vendor. Which doesn't bother me, I would never, ever call Citrix for help on XS. But for most shops, that's a show stopper.
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@olivier said in Xenserver and Storage:
That's why I asked if you have better knowledge of community on this solution because I really don't. So if it's the case, that it's not stable (darn, it's here since a long time!), that's indeed not an option.
Issue with HA lizzard is that it doesn't have a stateful quorum system (just pinging a single IP address). You can split brain it.
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@storageninja said in Xenserver and Storage:
@olivier said in Xenserver and Storage:
That's why I asked if you have better knowledge of community on this solution because I really don't. So if it's the case, that it's not stable (darn, it's here since a long time!), that's indeed not an option.
Issue with HA lizzard is that it doesn't have a stateful quorum system (just pinging a single IP address). You can split brain it.
Afaik latest ha-lizzard docs suggest to work in active-passive only... There must be a reason...
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@matteo-nunziati said in Xenserver and Storage:
@storageninja said in Xenserver and Storage:
@olivier said in Xenserver and Storage:
That's why I asked if you have better knowledge of community on this solution because I really don't. So if it's the case, that it's not stable (darn, it's here since a long time!), that's indeed not an option.
Issue with HA lizzard is that it doesn't have a stateful quorum system (just pinging a single IP address). You can split brain it.
Afaik latest ha-lizzard docs suggest to work in active-passive only... There must be a reason...
Can still happen.
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Almost any vSAN works pretty the same way which is just mirroring the data and caches between two or more hosts and keeping those intact. The above mentioned StarWind Free https://www.starwindsoftware.com/starwind-virtual-san-free is a great fit for 2-node deployments since it is capable of running on top of hardware RAID and has some intelligent split-brain protection either over additional Ethernet link or using a witness node. The nice thing is that you still have community support even with free version. XOSAN/GlusterFS is an overkill here (not talking about the performance) and using/supporting DRBD-based scenario looks like shooting in the foot for me unless you are completely familiar with it and know what you are doing.
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It's not overkill on user side, and we built it to be able to grow in one click. Have you ever even just checked how easy it's easy to deploy XOSAN? It's really few clicks
And it's second time I heard about the "intelligent split brain" management on StarWind but didn't see any paper nor a start of explanation about how it works (nor even a simple link). Can you elaborate please? If it's the witness node, it's the classical thing, but I'm curious about the split brain protection without using a witness node.
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@olivier said in Xenserver and Storage:
And it's second time I heard about the "intelligent split brain" management on StarWind but didn't see any paper nor a start of explanation about how it works (nor even a simple link). Can you elaborate please? If it's the witness node, it's the classical thing, but I'm curious about the split brain protection without using a witness node.
My understanding is they can do multiple links, multiple heartbeats,
Or a discrete and Stateful witness service on a 3rd system that will completely solve the problem.
VMware vSAN prevents this on 2 node and stretched clsutering by keeping witness components with sequence numbers on the witness system. In a vote is called the one has a updated sequence number matching the winner that side wins. In the event a stretched cluster partitions and both have matching sequence numbers the "Primary" side wins.
I'd argue isolation behavior goes beyond the storage heartbeat to how isolation is handled at the VM and Hypervisor level. STNITH is kind of a barbaric way ot handle this in 2017.
Other fencing systems that exist in VMware are for HA. Pings between hosts (Default on management network, moved to vSAN network if in use) Isolation address's (can have multiple) and heartbeats through datastore heartbeats (a file that is updated) for non-vSAN datatsore's. Based on this you can configure different VM and host isolation responses (maintain power, power off, shut down etc).
