Hi there!
I'm a newbie, so don't blame me fast :)
I have few questions related to Hypervisor's local disk passthrough to VM strategies
Preamble: we found vmdisk hook most comfortable way to use as a "gate to local
storage functionality" in shared clusters.
Let's assume, You have
A. 2 or 4 TB large SSD, which You need to split on different usages: some diskspace
provide for SQL / ETCd / Mongod etc. It must be fast, so no network in between. You have
only one physical disk, so you can't passthrough whole of it to single VM. So you make
LVM, and passthrough LVMs using vmdisk - this is how we did on some setups.
B. 2 or 4 TB HDD for gluster bricks.
At the end, You have few VMs, which "dies" together with Hypervisor, but most of
VMs can live migration. In together with L7 application level fail-over, it can lead to
non-critical level services level cluster, which is not so hard to throw in maintenance
Yes, it does not work at real device speeds: simple dd operation with unpartitioned block
device performs 3-4 times slower in VM, than on hypervisor. But, ability to mix workloads
(migratable VMS with non migratable) within small cluster of hypervisors is more
important, at some setups.
So, there are questions coming...
1. As far as I understand, there is possibility to replace vmdisk-hook vith cmdline. But I
didn't found a way, how to get it working. I always ended with "Could not open
'/dev/***': No such file or directory." which I could not avoid anyhow. May
be, someone can point me to an article or other thread, where there are clues, how to do
that?
2. what's the story behind vmdisk hook? As far as I understand from
https://github.com/oVirt/vdsm/blob/master/vdsm.spec.in its deprecated? Why? It is replaced
with some functionality? Why did VDSM's hook repo been deleted from github (in order
to avoid confuse?)?
3. Is it possible to achieve with any hook or some other instrument near hypervisor's
performance of local disk? We are ready for inconveniences like custom setup handling /
patches and so on
Thanks in advance!
It worked in 4.3.10 / CentOS 7, but the