Hola, yo soy Elver Sena Sosa and now we're going to talk about data placement
in vSAN and this is one of the those, important topics doing the same when it
comes to vSAN. Because, one question that I get a lot from customers is "where is
my data?" So how does vSAN go about it? And the easiest way to think of it is, vSAN cares about one thing or primarily about one thing is this groups, right?
vSAN forgets the host for now and only cares about these groups. So let's
say that you have a virtual machine and you either create that virtual machine from
scratch or use Storage vMotion on that virtual machine into a vSAN
datastore. You create the VM put it on the vSAN datastore or you Storage
vMotion on that VM. So we have the virtual machine and I put the VMDK on the
outside of the VM to visually see a visual, visually see it better. And let's
assume, that you power up or you moved it. vSAN the first thing is
gonna go is go say okay, I have an object the VMDK. Let's forget about the other
VM files for a second. I have an object where can I put it?
So vSAN is gonna go okay let me look at all my data disk groups all of
them I'm gonna put it somewhere. I can put it here, here, here, here, here. It
really doesn't matter where. What matters is the vSAN is gonna make sure that
these groups are more or less balanced through the lifecycle of the
throughout the whole whole operation or the daily routine. So that performance
will be symmetrical or similar regardless on which this group you put
it in. Which by the way that's another reason why you want the home this group
to be homogeneously configured. So let's say that vSAN chooses this this
group right here. Okay? And this object gets dropped
in this this group and you have that objects component restore in this disk
group. So how does vSAN actually do this thing after that happens? Well, let's
say that VM does a right, to the VMDK in reality, that right is captured by the
kernel on the host. The kernel in the host is gonna go okay
I got an iSCSI command from that VM right, so in which
data store is that, is that our VMDK? Oh, that VMDK is in the vSAN data
store therefore the kernel is going to go and say hey this vSAN process come in
and process this command. vSAN process comes in, he comes in and says okay I see
that I have this object and I need to send this rights to this block where are
they? And the vSAN process is going to go oh they are on this host. So the
design process is gonna create a vSAN packet put those right
instructions inside the vSAN packet and he's gonna send that over the
network. To the other host the vSAN process in the other host. The vSAN
process on the other host is gonna receive those packets and go okay I had
this block in which, which objects that they belong to which component? And in
what this group is that in. So he's gonna go send it to the disk group where those
blocks belong the cache in that this group is gonna reply and go okay we got
it done. The vSAN host the host is hosting those components then it's going
to reply back to the original requester and go hey we're done, we got this. At which point
the vSAN process is gonna tell the kernel module, the ESXi base the
hypervisor, hey we're good. At which points the hypervisor tells that the VM
we are good which is the equivalent of the VMDK the hard drive, telling the VM
the right has been completed. And that's how data placement works in vSAN
cluster. Thank you for watching. Yo soy Elver Sena Sosa. Have a good day.