XenServer hyperconverged
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@dustinb3403 I suppose you speak about the 2 XS host setup. It's only in this case you need an arbiter, and it will be on one of the 2 host (to avoid split brain).
If only your arbiter VM is down, quorum is still met (2 on 3). If you lose more than 1/3 of nodes (arbiter or not), you are on read only (protecting against split brains).
And no, you are not correct: each disk picture is a XenServer host. There is a XOSAN VM controller on each host (and an extra arbiter ONLY in 2 hosts scenario, if you grow the XOSAN from 2 to 4, no more arbiter, it's automatically removed)
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I asked to modify the picture to draw a host with the disk inside to avoid confusion
Thanks for the feedback on that guys 
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I haven't read the docs so this might be a stupid question...
Orange, Yellow & Pink each contain 2 hosts, correct?
You need to always add 2 hosts every time you scale up/out?
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@olivier said in XenServer hyperconverged:
And no, you are not correct: each disk picture is a XenServer host. There is a XOSAN VM controller on each host (and an extra arbiter ONLY in 2 hosts scenario, if you grow the XOSAN from 2 to 4, no more arbiter, it's automatically removed)
OK that is what I assumed in a private chat, that each disk image, inside of each orange, yellow and pink box was it's own server.
I also mentioned that in a PM that each server in the pool would have it's own witness.
The picture is a bit confusing though. (glad you asked for an more clear depiction)
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@fateknollogee said in XenServer hyperconverged:
You need to always add 2 hosts every time you scale up/out?
Good question.
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@fateknollogee If you are in replicated-2, you can add:
- 2 hosts to create a new extra RAID1 (bottom of a RAID0), creating a distributed-replicated (2x2)
- 1 host to go from replicated 2 replicated 3 (data is copied on three hosts, so it's a 1x3)
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@olivier said in XenServer hyperconverged:
@fateknollogee If you are in replicated-2, you can add:
- 2 hosts to create a new extra RAID1 (bottom of a RAID0), creating a distributed-replicated (2x2)
- 1 host to go from replicated 2 replicated 3 (data is copied on three hosts, so it's a 1x3)
So you can scale in any fashion you want.
What are the benefits to scaling with 2 hosts at a time?
What are the benefits to scaling with only a single host at a time?
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@dustinb3403 Scaling at one host: going on "triplicate" (same data on each node, you have 1/3 of total disk capacity, but you can lose 2 hosts and still have data access).
Scaling by adding 2 hosts at the same time: it's adding a subvolume, so more space.
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Lets say I go from 6 hosts (like your pic above shows- Brown/Yellow/Pink) to 8 hosts...
Does the existing data get rebalanced/redistributed across all 8 hosts?
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@fateknollogee yes
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@olivier said in XenServer hyperconverged:
@fateknollogee yes
And how many copies of the data exist? I.E. how many nodes can be shut down before you loose access to data?
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@dashrender As far you don't lose a complete mirror (2 hosts on the same pair), no problem. So on 8 nodes, it means up to 4 hosts if there in one by mirror.
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@olivier So you only gain in capacity scaling in 2's? Again as I mentioned earlier I'm curious how the Write suspension functions during failure....
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@olivier said in XenServer hyperconverged:
@dashrender As far you don't lose a complete mirror (2 hosts on the same pair), no problem. So on 8 nodes, it means up to 4 hosts if there in one by mirror.
and what happens if you do loose an entire mirrored pair?
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Where will XOSAN exist in this pricing structure?
https://xen-orchestra.com/#!/pricing -
@olivier what happens if you add in a single host, and then later add another host so you have an even number.
Would you eventually get more storage?
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@dashrender The same thing as if you lost a mirrored pair with RAID1 or 10.
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@fateknollogee said in XenServer hyperconverged:
Where will XOSAN exist in this pricing structure?
https://xen-orchestra.com/#!/pricingI believe it was mentioned as being a separate price entirely. So you can get XOA with or without XOSAN.
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@r3dpand4 said in XenServer hyperconverged:
@olivier So you only gain in capacity scaling in 2's? Again as I mentioned earlier I'm curious how the Write suspension functions during failure....
Write are suspended few secs, works fine. Tested on Linux and Windows VMs.
@dashrender said in XenServer hyperconverged:
@olivier said in XenServer hyperconverged:
@dashrender As far you don't lose a complete mirror (2 hosts on the same pair), no problem. So on 8 nodes, it means up to 4 hosts if there in one by mirror.
and what happens if you do loose an entire mirrored pair?
If you lose an entire mirror pair, it's like in RAID10: you will lose data.
@fateknollogee said in XenServer hyperconverged:
Where will XOSAN exist in this pricing structure?
https://xen-orchestra.com/#!/pricingNope, it will be a dedicated pricing, per pool, without number of hosts or disk space limitations.
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@dustinb3403 said in XenServer hyperconverged:
@fateknollogee said in XenServer hyperconverged:
Where will XOSAN exist in this pricing structure?
https://xen-orchestra.com/#!/pricingI believe it was mentioned as being a separate price entirely. So you can get XOA with or without XOSAN.
XOA Free at least to get XOSAN (you need XOA to deploy and manage it).
