VSAN Part 14 – Host Memory Requirements

For those of you participating in the VMware Virtual SAN (VSAN) beta, this is a reminder that there is a VSAN Design & Sizing Guide available on the community forum. It is part of the Virtual SAN (VSAN) Proof of Concept (POC) Kit, and can be found by clicking this link here. The guide has recently been updated to include some Host Memory Requirements as we got this query from a number of customers participating in the beta. The actual host memory requirement directly related to the number of physical disks in the host and the number of disk groups configured on the host. If you want to know more about disk groups, have a read of an article that I wrote about disk groups on the vSphere storage blog. Note that these are minimum host memory requirements but VSAN will not actually consume all of this memory.

At a minimum, it is recommended that a host has at least 6GB of memory. If you configure a host to contain the maximum number of disks (7HDDs x 5 disk groups), then we recommend that the host contains 32GB of memory. The following table, which can also be found in the Design & Sizing Guide, shows various combinations of disks and disk groups and the corresponding memory requirements.

Memory Amount (GB)

Max Number of Disks

Max Number of Disk Groups

Max Number of Disks per Disk Group

6

2

2

2

8

5

5

5

12

10

5

7

16

15

5

7

20

20

5

7

24

25

5

7

28

30

5

7

32

35

5

7

8 thoughts on “VSAN Part 14 – Host Memory Requirements

  1. Cormac – is this additional memory that should be installed on the host to account for resources that VSAN will be consuming? Any guidance on extra CPU capacity needed when running VSAN on a server.

    • No – this is total memory Tom. For CPU, VSAN will never use more than 10% of host CPU resources. Therefore you should plan appropriately and dedicated 10% to VSAN just to be on the safe side. More in the VSAN Design & Sizing Guide mentioned in the post.

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    • Hi Junian,

      From the information I have found so far, the answer is no. There is no relationship to capacity, simply number of disks and number of disk groups.

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