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ludz1
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Database server on VSAN with thin provisioned default storage policy

A question on deploying best practices for database servers, to memory thick provisioning is/was standard.

Today with an all flash VSAN cluster is best practice still to have it thick provisioned ?

any thoughts?

Thanks

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TheBobkin
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Hello ludz1

It shouldn't have any noticeable difference being eager-zero thick versus thin as there is no first-write penalty on vSAN (as was one of the main reasons for using eager-zero thick) nor any system that utilises Flash-based storage (e.g. as vSAN does at the bare minimum for cache-tier).

EZT Disks with VSAN, why would you?

Note that using 'Thick' with Storage Policy (e.g. Object Space Reservation=100) doesn't zero out the blocks - it just reserves them.

Bob

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TheBobkin
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Hello ludz1

It shouldn't have any noticeable difference being eager-zero thick versus thin as there is no first-write penalty on vSAN (as was one of the main reasons for using eager-zero thick) nor any system that utilises Flash-based storage (e.g. as vSAN does at the bare minimum for cache-tier).

EZT Disks with VSAN, why would you?

Note that using 'Thick' with Storage Policy (e.g. Object Space Reservation=100) doesn't zero out the blocks - it just reserves them.

Bob

ludz1
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Thanks Bob, you aware of any white papers that might reference this?

I cannot find much tbh, VMware vFabric Postgres 9.2 white paper doenst mention VSAN or flash based storage but states "Configure the VM to use the PVSCSI disk driver and use thick and eager-zero virtual disk formats."

cheers.

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TheBobkin
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Hello ludz1​,

Whether it improves anything or not, some Guest-OS/implementations require/recommend EZT disks (e.g. Oracle RAC with multiwriter on the vmdk(s)), in this case there are some additional steps that need to be taken (e.g. using vmkfstools -w to zero the allocated blocks):

VMware Knowledge Base

Migrating an Oracle RAC Cluster using Storage vMotion to vSAN Storage – Private Investigation - Virt...

If the implementation you are considering advises PVSCSI controllers on the VM(s) then I would certainly advise using these as generally these are not going to be advised unless they suit the workload/perform better.

Bob

nrsc0202
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If this question is related to Microsoft SQL Server:

According to the "BEST PRACTICES GUIDE – AUGUST 2018 ARCHITECTING MICROSOFT SQL SERVER ON VMWARE VSPHERE® Best Practices Guide"

on page 52:

"Set object space reservation: Set to 100 percent. The capacity is allocated up front from the vSAN datastore."

The VM can be Thin provisioned, but the storage policy should be set to reserve the space up front.

Link to the guide:

https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/solutions/sql-server-on-vmware-bes...

ludz1
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Thanks Bob

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ludz1
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Thanks nrsc0202​, its postgres but thanks, yeah as Bob says it doesn't zero out the blocks - it just reserves them.

Cheers,

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