That resource library is really light on content. How did StarWind Virtual SAN solve their manual backup problem?

"High performance and data high availability (HA) were not the only benefits for the company, meaning StarWind support t hat continues to solve the problems with ease."

Is having to contact support for problems with the VSAN another benefit?

It might as well say:
Problem: Company needs to make a stew.
Solution: Company bought a pot.

@Vlinderbeest said in Infrastructure Needed for Hypervisor Cluster:

@scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:

Clustering is done when the cost of clustering is low versus the risk of not clustering.

I would change that slightly to Clustering is done when the cost of clustering is low versus the cost of not clustering. A risk is always a cost, but some costs are not risks. For example taking down a hypervisor for maintenance vs moving guests to another node and taking down a free node for maintenance.

Sure, using risk cost vs investment cost as cost v cost is a perfect valid way to look at it. I use that all the time in the opposite way.

You can say that risk is a cost. Or conversely, you can look at the clustering cost up front as essentially a "financial event" similar to an outage.

@Dashrender Okay let's retake a clean example: one VM in a SR, with one 4GB VDI:

# lvscan inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/MGT' [4.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-770ceeac-e97e-4e05-b9c5-892b97b9d16e' [4.02 GiB] inherit

After first snapshot:

# lvscan inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/MGT' [4.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-38e2156f-da74-4edb-ac83-56fda54cfe55' [1.75 GiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-770ceeac-e97e-4e05-b9c5-892b97b9d16e' [4.02 GiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-f18856a5-039b-4d84-bf6c-a259d0f49a9e' [8.00 MiB] inherit

After second snapshot:

# lvscan inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/MGT' [4.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-38e2156f-da74-4edb-ac83-56fda54cfe55' [1.75 GiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-f18856a5-039b-4d84-bf6c-a259d0f49a9e' [8.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-770ceeac-e97e-4e05-b9c5-892b97b9d16e' [4.02 GiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-68408f33-5a69-4b3b-afdd-a2cfabcad9ba' [8.00 MiB] inherit

As you can see, we got a second 8 MiB logical volume, nothing more (base parent and active VDI doesn't change).

Let's remove the latest snapshot:

# lvscan inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/MGT' [4.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-38e2156f-da74-4edb-ac83-56fda54cfe55' [1.75 GiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-f18856a5-039b-4d84-bf6c-a259d0f49a9e' [8.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-770ceeac-e97e-4e05-b9c5-892b97b9d16e' [4.02 GiB] inherit

It removes the previously created volume, as expected. Now, let's remove the initial snapshot. Durin few seconds, we'll have this:

lvscan inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/MGT' [4.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-38e2156f-da74-4edb-ac83-56fda54cfe55' [1.75 GiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-770ceeac-e97e-4e05-b9c5-892b97b9d16e' [8.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/leaf_770ceeac-e97e-4e05-b9c5-892b97b9d16e_38e2156f-da74-4edb-ac83-56fda54cfe55' [4.00 MiB] inherit

But it will be automatically "garbage collected" when the system will see than the chain doesn't have any snapshot in it (after few seconds in this case):

# lvscan inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/MGT' [4.00 MiB] inherit inactive '/dev/VG_XenStorage-e27c48de-509f-3fec-d627-7f348062ab1a/VHD-770ceeac-e97e-4e05-b9c5-892b97b9d16e' [4.02 GiB] inherit

We are back to the initial situation.

I have three servers, though two would be fine. I don't have what I understand as a "reliable failover system" or anything close to it, but if one server is down I am in a position to provide a degraded or limited service using the other server(s) which is generally enough to keep users happy and the business ticking over. It's in no way automated or anything like high availability, but it gives me options and in a crisis I like to have as many options as I can. The cost isn't anywhere near double, since you're not doubling up on disks or memory or CPU by spreading the load across two boxes.