XenServer hyperconverged

vhinzsanchez

Just bumping up. Hopefully, Olivier will have some favorable update.

EDIT: corrected olivier...my apologies

olivier

Well, sort of This command is now working:

xe sr-create name-label=XOSAN shared=true content-type=user type=xosan

Still a lot of stuff between this and a viable product, I'm in the middle of testing the solution in terms of resilience and overhead. I need also a layer of glue to at least semi-automate the deployment of XOSAN on a pool, otherwise I'll spent to much time doing it manually for each beta tester ^^

Anyway, developing a storage on current storage architecture of XenServer is really a pain. Eager to see SMAPIv3 in action

vhinzsanchez

Thanks @olivier

Just finished reading your blog with response to comment referring to January for beta...I think it's too early in January. Getting excited here just by reading. Nice idea/product, btw.

More power!

olivier

I still have 27 days to stay in track

olivier

Just a new blog post talking about Erasure Code solution for XOSAN: https://xen-orchestra.com/blog/xenserver-hyperconverged-with-xosan/

AKA a great solution to mix security, space available and scalability

Just bought 10GB network stuff to dig on perfs.

FATeknollogee

This is so schweeeeet...
Let's get cracking on the beta testing.....
Where do I sign up, I've got a SuperMicro 2U quad node box waiting & ready

olivier

The setup is still to manual to be open for a "large scale" test.

But tell me more on your setup, I can start to think what's the best mode in your case

FATeknollogee

I'll send that to you via email so I don't clutter this thread

olivier

Sure, go ahead.

olivier

Article is out (as 5.12): https://xen-orchestra.com/blog/improving-xenserver-storage-performances-with-xosan/

Doc updated: https://xen-orchestra.com/docs/xosan.html

R3dPand4

@olivier Have you tested how it behaves if you shut down both hosts and then fire them back up? Do you have either of them weighted or master/slave? Suppose you have to replace an entire node, do you just mount the XOSAN and it begins replicating? Sorry if I'm jumping way ahead, but this is very interesting.

olivier

If you shutdown all XOSAN VMs, your SR is unreachable. When you start it, as soon the minimal number of nodes is up, it will work again (even if there is auto healing, it will be slower but work in R/W)
If you replace one node, you can do it live (we have a "replace" button in the UI!). The new node will replace the old one and get all the missing pieces via the heal process.

In the end, nothing to do to make it work again

Dashrender

What if you shut down host 1 now, and host 2 an hour from now, then power one host 1? Will the system just run now with the old data?

olivier

@Dashrender Can you be more specific on the total number of nodes from the start?

DustinB3403

@olivier I think this is a 2 node setup that @Dashrender is discussing.

Can the system scale to more than 2 nodes?

Dashrender

@olivier said in XenServer hyperconverged:

@Dashrender Can you be more specific on the total number of nodes from the start?

Let's assume your picture, 6 total nodes, but only 2 copies of data. So assume node1 in orange is shutdown, then 1 hour later node2 orange is shutdown. What happens?

How about a 2 node setup? i.e. no other witnesses to the configuration.

olivier

@dustinb3403 said in XenServer hyperconverged:

@olivier I think this is a 2 node setup that @Dashrender is discussing.

Can the system scale to more than 2 nodes?

This IS meant to scale (up to max pool size, 16 hosts, which is more a XenServer limit than ours )

@Dashrender The picture is not clear maybe: each "disk" icon is not a disk, but a XenServer host. So you have 6 hosts there. When you lost "enough" hosts (2 replicated hosts in the 6 setup, in the same "mirror"), it will be in read only. As soon one of this 2 is back online, R/W is back.

On a 2 node setup, there is an arbiter VM that acts like the witness. If you lose the host with the 2x VMs (one arbiter and one "normal"), you'll go in read only. No split brain possible.

Dashrender

In this picture
https://i.imgur.com/VKOVnkU.png

how many systems have the data on it? only 2?

DustinB3403

@olivier said in XenServer hyperconverged:

@dustinb3403 said in XenServer hyperconverged:

@olivier I think this is a 2 node setup that @Dashrender is discussing.

Can the system scale to more than 2 nodes?

This IS meant to scale (up to max pool size, 16 hosts, which is more a XenServer limit than ours )

@Dashrender The picture is not clear maybe: each "disk" icon is not a disk, but a XenServer host. So you have 6 hosts there. When you lost "enough" hosts (2 replicated hosts in the 6 setup, in the same "mirror"), it will be in read only. As soon one of this 2 is back online, R/W is back.

On a 2 node setup, there is an arbiter VM that acts like the witness. If you lose the host with the 2x VMs (one arbiter and one "normal"), you'll go in read only. No split brain possible.

The question is (i think) if you lost all hosts in the orange group, would XOSAN and the operating VM's in the entire pool still be functional Read/Write until those servers are brought back online?

R3dPand4

@olivier So you just can't make any writes during this period of node failure/recovery? Are the writes cached? If so how much can be cached and for how long?