Xenserver and Storage



  • So currently I have 2 HP servers that are being used and XenServer hosts. The shared storage is on an HP MSA1040 SAN, connected via 8Gb/s Fiber.

    The servers have worked flawlessly since I got them, not a single issue and have only been re-booted for updates and upgrades. I cannot say the same for the SAN. It has gone done about 4 or 5 times, and these outages have highlighted the fragility of my setup.

    The HP servers have 24 2.5" drive bays. So I am contemplating filling them with drives and moving away from the SAN, but in order to that I would need the space to be shared between the two hosts.

    How can I do that? What would that look like? What kind of cost would it be (outside of buying the drives) and is it a good idea?

    Someone mentioned VSAN to me while I was talking about this, but I am not that clued up about VSANs and how they work or how they are put together.

    Any advice on this would be greatly appreciated. But please don't lecture me on how bad a SAN is, and that my setup is doomed or that I am an idiot for doing it this way. I am looking for a path forward and not a beratement for things that have long since passed.



  • Not sure of your timeframe, but XOSAN is currently in beta.

    There are likely other local storage solutions that will work. Tagging @olivier and @scottalanmiller for additional input.



  • I don’t really know much about this stuff myself, that said hiring someone/a contractor who is completely hardware/software independent to make recommendations for you will likely end you up in the best and likely least expensive for your situation place.

    You might spend a few thousand on the consultant but they can easily save you tens of thousands by not buying the wrong thing.



  • Don't really have a time frame right now, but probably won't happen till after July 1, so something like 10 - 12 months from now.



  • How much storage do you need (allow for future growth)? Is HA required? If not, you could likely get away with using XO's Continuous Replication feature.



  • @danp said in Xenserver and Storage:

    How much storage do you need (allow for future growth)? Is HA required? If not, you could likely get away with using XO's Continuous Replication feature.

    I think I would like HA enabled, as for capacity, we currently have 12Tb useable on the SAN, and use around 4.7Tb of it (well allocated, actual use is around 4.9Tb). So I am thinking 10Tb or more would suffice.



  • Indeed, XOSAN could fill the gap and create a "VSAN" like solution.

    However, if you don't plan to get bigger than 2 hosts, you can also take a look a "HA lizard" (which is basically a DRBD block replication between 2 local storages).

    Anyway extra questions:

    • do you have RAID support in your XS host machines?
    • would you like to add hosts in the future? (if you think it's yes, HA lizard is out of the equation)


  • @olivier said in Xenserver and Storage:

    Indeed, XOSAN could fill the gap and create a "VSAN" like solution.

    However, if you don't plan to get bigger than 2 hosts, you can also take a look a "HA lizard" (which is basically a DRBD block replication between 2 local storages).

    Anyway extra questions:

    • do you have RAID support in your XS host machines?
    • would you like to add hosts in the future? (if you think it's yes, HA lizard is out of the equation)

    Yes, there is RAID support in the two hosts. And no I do not think I'll be adding hosts anytime soon. We have plenty of growth in these two hosts.



  • @olivier said in Xenserver and Storage:

    would you like to add hosts in the future? (if you think it's yes, HA lizard is out of the equation)

    I believe HA Lizard is not limited to two hosts.



  • @jrc So HA lizard could do the trick in your case (or you can set ip up manually, basically DRBD between 2 hosts)



  • @danp I don't think it could do more than that because that's block replication without a cluster FS.



  • @olivier From their FAQ --

    Is HA-Lizard only for 2-node pools?

    No. HA-Lizard works with any number of hosts within a pool and provides reliable high availability in a 2-node pool.



  • It very likely means: replicate blocks are made on 2 nodes, and then other pool members are connected to this setup. It doesn't mean storage is scaled on all local SR within all hosts.

    That's also something you could do on XOSAN: use a limited number of hosts to store data (from 2 to n). But you could also use all of them.

    So in HA Lizard case, it means if you lose 2 hosts on a 16 pool for example, your data is gone.

    Hope it's more clear this way 🙂



  • Halizard can work, but I'd highly recommend paying for support. I had issues with it, and while support was awesome, it's not something worth deploying yourself.



  • You could also look at starwinds vsan and use either a windows controller on each server, or go with the linux controllers that they recently released.



  • @dustinb3403 said in Xenserver and Storage:

    You could also look at state d's vsan and use either a windows controller on each server, or go with the linux controllers that they recently released.

    State D?



  • @reid-cooper spellcheck on mobile, I corrected it. Starwinds.



  • That makes a bit more sense.



  • @olivier I would not do HA Lizard, it is problematic with XenServer. You can ask @StorageNinja . I have gone through many SW posts having issues with this. I did recommend it once but it was not worth it. XOSAN will be much better
    https://xen-orchestra.com/blog/xenserver-hyperconverged-with-xosan/
    or if you can afford two more host with WIndows Server and StarWind VSAN then it would be good too.





  • @dustinb3403 Even more amazing!! Thanks for the share. I didn't know.



  • @dbeato said in Xenserver and Storage:

    @dustinb3403 Even more amazing!! Thanks for the share. I didn't know.

    Yup, pretty much makes the setup impossible to beat, as you don't ever need to introduce Microsoft into the environment.



  • Can someone give me an overview what a VSAN setup would physically and software wise look like. Sounds like there is a controller involved, would this run on the host? Both hosts? Stand alone hardware?

    What is the general cost for Starwind's VSAN stuff? Is it a perpetual licence or a per year thing?


  • Service Provider

    @jrc said in Xenserver and Storage:

    What is the general cost for Starwind's VSAN stuff? Is it a perpetual licence or a per year thing?

    They have totally free versions.



  • @jrc said in Xenserver and Storage:

    Can someone give me an overview what a VSAN setup would physically and software wise look like. Sounds like there is a controller involved, would this run on the host? Both hosts? Stand alone hardware?

    What is the general cost for Starwind's VSAN stuff? Is it a perpetual licence or a per year thing?

    Paging @KOOLER


  • Service Provider

    @jrc said in Xenserver and Storage:

    Can someone give me an overview what a VSAN setup would physically and software wise look like. Sounds like there is a controller involved, would this run on the host? Both hosts? Stand alone hardware?

    It's SAN run on the hosts. VSAN just standard for Virtual SAN. It's really SAN, but it doesn't have any appliance associated with it, so you don't take on all of the risks of external storage, because it is stored on the hypervisor.



  • @jrc you'd have a VM on each host, running the VSAN software. They'd pool the resources from all of your servers.

    Only your hypervisors would be the things needed. No dedicated cabling between the systems, no custom switches, no external storage.

    Everything is hyperconverged between your available servers.


  • Service Provider

    If you put VSAN on stand alone hardware, it turns back into normal SAN.



  • So you have a VM on each host, and you give it all the local storage. It then allows you to connect the host to it via some protocol (iSCSI, NAS etc)? Or does the VM has some sort of extra hook into the OS to manage and share the storage?

    Does it basically just keep the storage volumes on each host synced and identical?

    What kind of overhead does this create (ie if I have 6Tb in each server, does that mean I actually only have 3Tb of usable space since I need 2 copies of everything, 1 for each server)?

    Is there a need for a dedicated link between hosts for sync traffic?

    Starwind's stuff is free, which is cool. Is the paid version particularly expensive? I am thinking support would be a good idea, if only for a year.

    This just sounds too easy and/or good to be true. As it sounds like I just need to add drives to my 2 hosts and setup some free software and I'd be set. So I am just making sure I know about as many of the considerations as possible before I run this up the flag pole for a budget.


  • Service Provider

    @jrc said in Xenserver and Storage:

    So you have a VM on each host, and you give it all the local storage. It then allows you to connect the host to it via some protocol (iSCSI, NAS etc)?

    It is VSAN if it uses iSCSI. It is VNAS if it uses NFS or SMB.