Couple of questions about storage settings

[wallewek]

A couple of optimization questions re: StarWind storage tuning.

1. Is there any particular reason to make sure that cache (RAM and L2) is configured the same on both/all VSAN partners? E.g., if one partner has more RAM or a larger SSD than the other, should one keep them the same, or optimize the settings on each host separately -- more L2 cache on the one with the bigger SSD, for example?

2. Is there any particular optimum or maximum portion of available space that should be allocated on a host partition for a thick NTFS image? If I understand correctly, unless one extends an image, the image file is totally static, and fragmentation of the host partition is pretty much irrelevant. Is that right? If so, I would think that allocating nearly all of the host partition to a single image would be just fine.

-- Ken

[Boris (staff)]

Ken,

Here are the answers to your questions

1. There is no obvious reason to make these values differ from each other, at least as far as L1 (RAM) cache is concerned. L1 cache is replicated between the nodes, and if you assign 6GB on one server and only 4GB on the other one, they will reserve 6GB and 4GB of RAM respectively. But the actual amount of cache used on both servers will be 4 GB, and 2GB will be reserved, but out of any use. In terms of L2 cache things look a bit different, as L2 cache is not replicated. Yet, as long as StarWind is all about mirroring the data, I would recommend to stick to identical configurations on both sides.

2. Your assumption about the StarWind image being static on the host's NTFS partition is generally correct. The changes appear to happen only inside the image file, but on the level of the host Windows OS this file is a thick-provisioned one and is not causing any fragmentation. If you are concerned about how much space you should allocate for the img file, I would say you need to have several GB spare on the partition where you are going to put that StarWind disk. So, you are right about assigning almost all space for that.

[wallewek]

Ah. Excellent. Very clear, informative answers. Thank you!

-- Ken

[Boris (staff)]

You are welcome anytime.