ChrisI88
Enthusiast
Enthusiast

ESXi 7u2 VMFS 6, LUN size greater 64TB questions

With out thinking I created a 108TB LUN on our Nimble storage array.   I was also able to create a 108TB VMFS 6 Datastore on it without a problem.   

First Question)  Should I have been able to do this ?  It there is a 64TB limit then shouldn't I have gotten a warning that I'm exceeding the 64TB ?

Second Question) What are the ramification of this?

Currently we have a single vm on this datastore with 2 very big drives (vmdks).  One at 50TB and the other at 25TB.

The VM is running fine and there don't seem to be a problem, but I'm wondering I should move the drives to 2 different datastores that are at or below the 64TB stated limit, though clearly not enforced.

Thanks.

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2 Replies
kastlr
Expert
Expert

Hi,

 

VMware Maximums doesn't automatically mean that they will be caused by a technical hard limit.

Some might also be set based on testing results or because supporting extreme configurations might require additional resources.  

But, even if it's possible to go beyond the maximums you shouldn't do so.

In case you would run into a problem VMware support will advice you to stay within the supported maximums or might even reject your support request because you didn't follow their recommendations.

 

May I ask what application or service hosted on a single VM would require such large vmdks?

Personally, I never would use vmdks of such size.

Any kind of filesystem repair/scan/upgrade might be a nightmare and could take awfully long.

Restore operations might be more complex when you can't provide another vmdk of similar size in case of an array error/problem.

 

If 

  • the VM would have a problem or
  • you have to apply minor/major updates/upgrades or
  • you have to patch the application/service or
  • other kind of maintenance tasks are required,

75 TB of data might not be accessible.

 



Hope this helps a bit.
Greetings from Germany. (CET)
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depping
Leadership
Leadership

You should. These are VMs tested limits, and that is what VMware Support will stick too typically.

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