datastore size

[sadom]

There are 5 5TB datastores in the vcenter 6.5 environment. We are using vnx storage. If I add 10 TB datastore to this structure, will it be a disadvantage? Or should I add 2 5TB datastores? So I want to ask this. It is better if the datastore sizes in the infrastructure are all the same size. And we user Storage DRS in the infrastructure.

[alantz]

If you are a small environment todays storage performs so well your datastore breakup really is just more of a logical breakup for your data, not so much for performance. Now maybe with large Enterprise layouts that changes, but for me I'm just a small fish in the pond.

--Alan--

[nachogonzalez]

As it was stated before, it's more of a logical structure than a performance optimization.
A few things that I would consider:
- Smaller LUNs take less time to restore. ( Basically if you have to restore 5 TB it takes less than restoring 10TB, in case they are full of course)
- Depending on your VM storage layout you might face some issues (For example, I have seen issues in the past when they assigned a 8TB thin provisioning VMDK to a 2 TB lun. You can play with overcommitment, and it's usually fine to have some, but in some cases you will have issues.)
If you have a business requirement to have a really large VMDK it would be nice that the Datastore backing it has enough storage space.

All of that being said, and if there are no special business requirements I would advise using 2 x 5TB luns so all your storage DRS cluster is consistent and has the same lun layout.

[khiregange]

Should we have many small LUNs or some large size LUNs for Storage DRS?

In fact, it depends. You could create 2x 64TB LUNs, 4x 32TB LUNs, 16x 8TB LUNs or 32x 4TB LUNs. When there are more datastores, SDRS will have more option to find right datastore to fit the virtual machine to placed or moved.
 

• More datastores in cluster > Better space and I/O balance
• Larger datastore size > better space balance
   

However, it does not mean that we should always go for many small datastores. It is better to try to find the the sweet spot for your environment by taking failure domain (backup restore time), IOps, queues (SIOC) and load balancing options for Storage DRS in to account.

KB - https://kb.vmware.com/s/article/2149938

Blog : - https://www.vmwarehelp.com

[khiregange]

a