Thin provisioning and Thick Provisioning - NetappNotes By ARK

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Thin provisioning: 

  Thin provisioning is used in large environment because we can assign the more space than what we have in current environment.

  If we take an example that, if you have 1TB storage space in SAN still you can allocate to the clients 1.5TB, if you enable the thin provisioning SAN will take only what you have used.

Clear example here.

if you clearly observe the above example after allocating 1.5TB of space to all the clients still we have available space, thin provisioning will take only used space in consideration.

Using NetApp Thin Provisioning

Thin provisioning is enabled on NetApp storage by setting the appropriate option on a volume or LUN. You can thin provision a volume by changing the "guarantee" option to "none." You can thin provision a LUN by changing the reservation on the LUN. These settings can be set using NetApp management tools such as NetApp Operations Manager and NetApp Provisioning Manager or by entering the following commands:

Volume: vol options "targetvol" guarantee none

LUN: lun set reservation "/vol/targetvol/targetlun"  disable

The change is instantaneous and nondisruptive.

When not to use thin provisioning. There are some situations in which thin provisioning may not be appropriate. Keep these in mind when deciding whether to implement it and on which volumes to apply it:

•     If the storage consumption on a volume is unpredictable or highly volatile
•     If the application using the volume is mission critical such that even a brief storage outage could not be tolerated
•     If your storage monitoring processes aren't adequate to detect when critical thresholds are crossed;  you need well-defined policies for monitoring and response
•     When the time required for new storage acquisition is unpredictable; if your procurement process is too lengthy you may not be able to bring new storage online fast enough to avoid running out of space

You can periodically initiate the space reclamation process on your LUNs. The GUI tool will first determine how much space can be reclaimed and ask if you wish to continue. You can limit the amount of time the process will use so that it does not run during peak periods.

Here are a few things to keep in mind when you run space reclamation:

•     It's a good practice to run space reclamation before creating a Snapshot copy. Otherwise, blocks that should be available for freeing will be locked in the Snapshot copy and not be able to be freed.
•     Because space reclamation initially consumes cycles on the host, it should be run during periods of low activity.
•     Normal data traffic to the LUN can continue while the process runs. However, certain operations cannot be performed during the space reclamation process:
•         Creating or restoring a Snapshot copy stops space reclamation.
•         The LUN may not be deleted, disconnected, or expanded.
•         The mount point cannot be changed.
•         Running Windows® defragmentation is not recommended.

Thick Provisioning: 

 Thick provisioning you can't use in large environments, because as soon as you allocate the space to the client it will reserve for the same client.

below is the clear example

If you clearly observe the above example as i have allocated 1TB space to the clients, after assign the space to clients there is no space is available in the SAN. Thick provisioning will not consider the used space it will only consider allocated space.

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