is it possible to mix different host that each has a different number of disk groups in the same VSAN cluster?
I
Example:
Existing VSAN cluster with 3 x R640 (Only 4 drive slots, assuming 2 disk groups). Get 2 new R740XD which can have up to 32 drives slot, can have more than 2 disk group.
Let say we plan to create 4 disk groups for R740xd.
Can we join R740xd nodes into the existing R640 VSAN cluster (2 disk groups per host only)?
Thanks
Hello Eddy,
"is it possible to mix different host that each has a different number of disk groups in the same VSAN cluster?"
Yes it is *possible* however it is not advised to have non-homogenous nodes in a cluster - one of the reasons for this is that if one node has for instance 40TB attached as capacity-tier and another only has 10TB, you could be 100% full on one nodes disks while the larger one is only 25% with the same amount of data on each. vSAN will of course attempt to relocate data off disks once they hit 80% full (default setting) but in your scenario it will be very lop-sided. Other things to consider - If you had 3 nodes with 10TB each and 1 node with 40TB, if the 40TB nodes fails you won't have any hope of being able to rebuild all data to FTT=1 and probably cause the remaining nodes to approach being completely out of space resyncing the data it can fit. Space to compute resource ratios would also be non-uniform if you configured it like this.
Bob
Hello Eddy,
"is it possible to mix different host that each has a different number of disk groups in the same VSAN cluster?"
Yes it is *possible* however it is not advised to have non-homogenous nodes in a cluster - one of the reasons for this is that if one node has for instance 40TB attached as capacity-tier and another only has 10TB, you could be 100% full on one nodes disks while the larger one is only 25% with the same amount of data on each. vSAN will of course attempt to relocate data off disks once they hit 80% full (default setting) but in your scenario it will be very lop-sided. Other things to consider - If you had 3 nodes with 10TB each and 1 node with 40TB, if the 40TB nodes fails you won't have any hope of being able to rebuild all data to FTT=1 and probably cause the remaining nodes to approach being completely out of space resyncing the data it can fit. Space to compute resource ratios would also be non-uniform if you configured it like this.
Bob
Dear Bob,
Thanks for your answer. It definitely answered my question. Ya, I thought of it might not be advisable to do this because of the imbalanced performance; I've overlooked the capacity and rebuild risks.
Initially, I thought I've seen somewhere stated the hosts within the same VSAN cluster need to be the same configuration including the number of disk groups or disk slots but I couldn't find it.
In short, I will say it is a NO for this kind of configuration.
Thanks again.
Eddy