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RanjnaAggarwal
VMware Employee
VMware Employee

Performance Impact in VSAN 6.2 in Different configuration changes

I want to understand what is performance impact when one is changing some settings in vsan cluster. I want to know to impact in below given cases:-

1. Performance impact on Existing VMs in vSAN datastore when storage policy gets changed?

2. When enabling or disabling deduplication and compression?

3. Enabling and disabling VM Swap Sparse setting?

Regards, Ranjna Aggarwal
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zdickinson
Expert
Expert

1. Performance impact on Existing VMs in vSAN datastore when storage policy gets changed?

This one is very "It Depends".  If you go from FTT = 1 to FTT = 2 for many VMs that will generate a lot of IO and could have a negative impact.  Even increasing stripe width could be negative.  Going from FTT = 2 to FTT = 1 could have no impact as you're just saying the least FTT = 1, it might stay at FTT = 2 if the space isn't needed.  If you're thinking about changing the default policy from FTT = 1 to FTT = 2,  I would do it on a group if VMs at a time manually and then changing the default.

2. When enabling or disabling deduplication and compression?

Good question, I would be interested in the answer, we don't have AFA.

3. Enabling and disabling VM Swap Sparse setting?

I don't think much at all.  By default the entire space for a VMs memory is reserved.  If you enable this setting and then power down and power on machines, it will only be created if needed.

Hope that helps.  Thank you, Zach.

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dhanarajramesh

swap spare setting is global setting and by default it is enabled and reserve 100% thick space. and when u disable become thin. so I hope, when you are changing it, would not affect the existing VMs setup and only take effect from new VM.

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RanjnaAggarwal
VMware Employee
VMware Employee

How much is this performance negative impact. Can i do this calculation with the help of any tool?

Regards, Ranjna Aggarwal
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