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73061
September 9th, 2014 02:00
Dell Compellent - VMware Virtual disk - Thin and Thick provisioned - Basic and Dynamic disks - best practice
Can anyone point me to documentation on best practices for in-guest disk formats?
I know the Compellent thin-provisions everything. However, in VMware 5.5, when setting up a virtual disk in the guest you have a number of choices:
- Thick provisioned lazy zeroed
- Thick provisioned eager zeroed
- Thin provision
Then again at OS level you have a choice of:
- Basic
- Dynamic
I would appreciate a pointer to technical document explaining the benefits/drawbacks of each choice and recommended best practice.
Kind Regards,
Kath
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bjbradley
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September 11th, 2014 21:00
I would do either thin or thick lazy zeroed. Both will take up the same amount of data on the Compellent. The main decision is where do you want to manage your storage? If you do thin on thin you have to make sure you do not over provision in both places. If you do thick lazy zeroed then you can only over provisioning on one side.
Saying that I always do thin on thin. Reclaiming space at the VM level is not officially supported right now, but maybe one day.
In a virtualized environment, always do simple. There is zero benefit for dynamic with virtualization
Kathy_H
11 Posts
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September 11th, 2014 05:00
I would really like to understand whether the in-guest disk should be basic or dynamic; what is best practice?
Kathy.
JBrunt
8 Posts
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September 15th, 2014 08:00
We do thick eager zeroed. It doesn't take up any more space on the compellent array, it causes traffic during the creation, but the array just ignores the zeros. It is the only method that doesn't take a write performance penalty in vmware when addressing new blocks.