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Contributor
Contributor

ESXi installation to iSCSI. Optimal LUN size?

Hello,

I am interested to make the ESXi 6.5 installation to a iSCSI LUN.

But which size should the LUN have?

VMware suggests minimum 5.2GB for installation disk. But what's recommended? I can't find a recommended size.

What do you think? 8GB, 16GB, anything else? Or will more than 5.2GB don't bring any advantage? So it should just be 5.2GB and that's it?

Or should the LUN maybe be even smaller than the 5.2GB so that ESXi will create the scratch partition on a local SSD?

Or is the better performance of the local SSD for the scratch partition irrelevant?

What will happen if there anytime the RAM of the ESXi get's full and it needs to swap? Will there be done any swapping to the iSCSI drive? In my case that would be very bad performance (1 Gigabit Ethernet).

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VMware Employee
VMware Employee

But which size should the LUN have? What do you think?

The minimum is the best starting point, though 8GB's is a nice even number to work with. Not much benefit going larger if you are going to keep all logging and scratch data on external storage and with default settings.

Or should the LUN maybe be even smaller than the 5.2GB so that ESXi will create the scratch partition on a local SSD?

Going below this can cause issues with upgrading the host.

Or is the better performance of the local SSD for the scratch partition irrelevant?

Higher performance for the scratch is not going to be noticeable.

What will happen if there anytime the RAM of the ESXi get's full and it needs to swap?

VM's will resort to swapping when RAM is low.

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