In this page, we are going to see frequently asked vmware questions. I am not going to segregate it into L1, L2 and L3 level. Because questions are purely depends on interviewer mindset. Even for L3 position you can expect very basic questions.
1.How you troubleshoot VM Performance issue?
These are from real time interview. will post answers soon..
Basics:
- What is Virtualization and why do we need it?
- What is HA and how it works?
- What is FT and how it works?
- What is DRS?
- Clone Vs Template Vs Snapshot
- What are the mandatory files for a VM to run ?
- Different type of Disk provisioning and its differnece.
Scenario Based Questions:
- We need to pull cpu, memory and storage performance report from vcenter.
- If cpu or memory utilization is high, involve OS team to check in OS level.
- If cpu ready value is high, that means we dont have enough resource available on ESXi host, migrate the VM to another host, if cluster is not having capacity add more capacity.
- If multiple VM’s are having high IOPS involve storage team to check.
2. What you will do when you see ESXi host shows not responding in Vcenter ?
- First and foremost thing is to check if VM’s are impacted.
- If vm’s are down, connect to ESXi console and check for any issue. (like PSOD or hung). Reboot the host immediately to bring it back online.
- Vm’s are online, but host is not responding means, try to connect ssh to the host and restart management services.
- If host is not available via ssh, check for any possible issues with network. only management network/gateway might be having issue.
3. How you will migrate host from VSS to VDS and vice versa without downtime ?
- create a vss or vds and create all port groups in new switch.
- Disconnect one up-link from vss/vds and connect to new vss/vds.
Note : If we don’t have two up-links and disconnect host from VSS downtime is expected. If we remove host from DVS, it will still function with proxy switch.
4. How you troubleshoot Vcenter performance issue?
- First and foremost thing is storage space on vcenter.
- CPU and Ram utilization on vcenter.
5. What will you do if host is not entering into Maintenance mode?
- We need to check VM’s running on the host.
- They may have vmware tools installer mapped, local iso mounted or disks are running on local disk.
- we need to fix the issue on vm’s, migrate all the VM’s from host and enter in Maintenance.
6. What are the possible causes for vmotion failure/errors?
- Check the vm and make sure it dont have any local iso mapped.
- It is not running vmware tools install.
- VM files are not under esxi host local storage.
- Both source and destination esxi host have vmotion enabled on vmkernel.
- Both source and destination hosts are able to communicate over vmotion network.
7. What will you do if VM is showing inaccessible/orphaned in inventory?
- Make sure vmx and vmdk files exist in datastore.
- Delete the VM from inventory and re-register it.