@travisdh1 said in Gluster and RAID question:
@biggen said in Gluster and RAID question:
@travisdh1 Great thanks for that info. When you say storage for VMs are you speaking of a SAN? So your VMs are running off the Gluster?
Yeah I thought 3 nodes of storage + the hypervisor node sounded like a ton of equipment. I know you can buy single boxes that have 2 - 4 nodes inside of them to reduce the footprint.
Something like that. Basically Gluster would replace the SAN.
Those 2-4 node in a boxes are just horrible solutions if you want fault-tolerance. Basically, you still have a single point of failure, but now it takes down all 3 nodes instead of a single node.
Yeah I've always wondered about that multiple nodes in one case setup. Especially since I'd imagine the PSU backplane is probably being shared between all the nodes inside in some fashion.
@Dashrender said in Gluster and RAID question:
@biggen said in Gluster and RAID question:
I appreciate the explanation guys. Not being in the IT field (directly) for some time means I'm playing catch up with a lot of the stuff.
Lets say as a hypothetical one wanted to build out a 500TB Gluster cluster to be used as a backup target for VMs. It looks like you need at least 3 nodes to build out the Gluster Cluster. Then, of course, you need an additional node for the hypervisor - so 4 nodes minimum.
On the three Gluster nodes, would you be installing a Linux OS directly to them (bare metal)? I know from reading here physical servers have fallen out of style. Is this a use case where a physical server still serves a purpose?
Once the Gluster volume is up and running, you could then connect the hypervisor to the cluster assuming the hypervisor had Gluster Client support and then you have the massive cluster attached to the hypervisor as a SR to be used appropriately.
I'm just wondering if something like this would work.
Why would you need a fault tolerant storage solution for your backups? i would think if it was that important - you'd more likely go to tapes as part of your backups D2D2T.
You probably wouldn't. I was just trying to dream up a solution of doing a three cluster Gluster. Perhaps a VM SR would be a better scenario OR perhaps a massive NAS storage Gluster cluster holding raw 4K footage for a production company. Again, it was a hypothetical. I have a hard time imagining any scenario where I would need to ever contain this much storage unless I'm starting up my own YouTube or some sort. The guys over on Reddit in the r/Datahoarder sub are commonly collecting hundreds of TB of junk but that is mostly on spare parts and cobbled together machinery. I've never seen any massive storage scale done with my own eyes using production level equipment and software so I guess its more curiosity on my own part as to how it would work.
@travisdh1 said in Gluster and RAID question:
@Dashrender said in Gluster and RAID question:
Question for those in the know - Can Gluster run on the same boxes as the hypervisor like in a hyperconveraged setup? It seems crazy to have a solution as @biggen is suggesting - 3 Gluster nodes and a single VM host using that Gluster cluster - i.e. SPOF in that one VM host.
And as he mentioned, that's a ton of hardware.
Yes. Really easy if using a linux based KVM. Just create your Gluster storage and mount it as your VM config and storage directory. I've not done a setup like this myself, so I'm probably missing some high-points, but that's the basic idea.
I know there are lots of ways to skin the cat, but wouldn't you still need three separate Gluster nodes? Gluster recommends at least three in order to avoid split brain. If you used a two physical node system I don't think they want you to do that without an arbiter which is something I have no idea about.
@Dashrender said in Gluster and RAID question:
@biggen said in Gluster and RAID question:
On the three Gluster nodes, would you be installing a Linux OS directly to them (bare metal)? I know from reading here physical servers have fallen out of style. Is this a use case where a physical server still serves a purpose?
This seems to be a misunderstanding. There's nothing wrong with physical servers. Something has to run on the physical hardware to make it work, I don't know diddily squat about Gluster, but I image it works something like this:
A Linux OS is installed onto some smallish disk, possibly SD card, that is used to setup a Gluster cluster.
KVM, or some other hypervisor is installed into the Linux OS as well, the hypervisor is pointed to the Gluster cluster for SR
VM's are made in that hypervisor.
Now I'm guessing this can't be done with Hyper-V, since that can't run inside Linux (as far as I know), so you'd be forced to have hypervisor hosts and storage hosts (i.e. SAN/NAS) for Hyper-V and other hypervisors.
I'm looking forward to someone shredding this post.
I don't know any about Gluster either other than what I've gleaned in the last 24 hours. From what I toyed with, I spun up two Debian VMs and installed and configured the Gluster volume from those two VMs. Then I could (I didn't though) install the Glusterfs client on xcp-ng in order to connect to the cluster and then the hypervisor uses the cluster as a SR.
If you were talking about ONLY two physical nodes for everything, then what you say makes sense. I think you'd have to install your base OS (Debian, Cent, whatever...) on each node, configure the cluster, and install the hypervisor inside the same OS on both nodes in order to utilize the cluster.
There is a split brain issue with only using two nodes from what I've read though.