Yellow Bricks

by Duncan Epping

vSphere and Service Console Memory

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Today I read something I have not seen anywhere else before. I have always been under the impression that the memory reserved for the Service Console was increased from 272MB to 300MB. Although the bare minimum is indeed 300MB there’s another side to this story, something I did not expect but actually does make sense. As of ESX 4.0 the allocated Service Console memory automatically scales up and down when there is enough memory available during installation. Let’s make try to make that crystal clear:

  • ESX Host – 8GB RAM -> Default allocated Service Console RAM = 300MB
  • ESX Host – 16GB RAM -> Default allocated Service Console RAM = 400MB
  • ESX Host – 32GB RAM -> Default allocated Service Console RAM = 500MB
  • ESX Host – 64GB RAM -> Default allocated Service Console RAM = 602MB
  • ESX Host – 96GB RAM -> Default allocated Service Console RAM = 661MB
  • ESX Host – 128GB RAM -> Default allocated Service Console RAM = 703MB

Lessons learned:

  1. Allocated Service Console memory is based on a formula which takes available RAM into account. (Haven’t found the exact formula yet, if I do I will of course add it to this article.)
  2. Always make your swap partition 1600MB; as an increase of RAM might automatically lead to a swap partition which is too small.

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Comments

  1. I guess you also need to think about this if you increase your ram in your host after instalation as the SC will not automatically assign more.

  3. Thanks for that information. I did not know this but since memory is relatively cheap in my eyes I always size my esx hosts Services console to have 800mb and a 1600mb swap.

  5. ESX Server 43.2mb = 1mb service console, according to the 128gb ESX = 703mb SC.

    While the percentage of the first one is 3.75, or 26.66mb ESX = 1mb SC. Aside formula, 43.2 / 26.66 = 1.62 times.

    If you apply the second formula of an 8gb ESX it becomes 185mb SC initial usage. But, perhaps it’s just shown to be 300mb for 8gb but in reality it scale has a true initial of 12.96gb ESX for 300mb?

  6. vCalendar 2.0 entry sneak preview:
    On an ESX4 host, the default amount of Service Console memory assigned is 400MB. The maximum value is 800MB. The minimum is 256MB although the documentation claims 300MB.

    The values for an ESX3 host are the same, except for the out of box default amount of memory which for ESX3 is 272MB. With the added features and bolt on products in vSphere, it’s easy to see why VMware found it necessary to up the default amount.

  8. @Chris Those are my findings on my lab equipment. While I doubt the MIN/MAX values change between different hosts, it sounds like the default value might.

  9. 400 the default? That depends on the amount of memory you are carrying. I’ve seen implementations where the default was 300. and technically speaking there is not default. it can be anything between 300 and 800 🙂

  10. I just did an v4 installation on blades with 32gig memory and all the SC memory was 500Mb. On machines with lower memory I have seen the memory at 300mb…but not lower.

  11. Does anyone know why they decided on an 800MB maximum for the Service Console? Is it a technical limitation or just something VMware came up with as they thought it would be enough? Not sure about anyone else, but I regularly see the SC using 600MB+.

  12. Hi guys,

    I’ve just installed 5 x ESX 4 (U1) with 64GB RAM. SC was set to 602 MB on them all.

    Summary page says it’s using 1860 MB with no VM’s…. greedy little thing isn’t it 🙂

  13. I just noticed this today when I was trying to figure out why my installation scripts were not sizing the memory correctly. I use the sed command to do a find and replace so this worked great in ESX 3.5 since it was static, but not so much now.

    sed -i -e ‘s/\/boot\/memSize = \”661\”/\/boot\/memSize = \”800\”/’ /etc/vmware/esx.conf
    sed -i -e ‘s/676864/819200/’ /boot/grub/grub.conf

    One thing to notice from above and to add to your chart –

    ESX Host – 96GB RAM -> Default allocated Service Console RAM = 661MB

    Greg

  14. My bad, in case anyone googles and tries to use this. Missed the middle line in the cut and paste.

    sed -i -e ‘s/\/boot\/memSize = \”661\”/\/boot\/memSize = \”800\”/’ /etc/vmware/esx.conf
    sed -i -e ‘s/661M/800M/’ /boot/grub/grub.conf
    sed -i -e ‘s/676864/819200/’ /boot/grub/grub.conf

  16. That means,if I am making script to change the value to 800,I have do modification to that script so that firt it should read the value of memory assigned and then change it to 800

  17. “Although the bare minimum is indeed 300MB”. The bare minimum for ESX 4.1 is still 272MB – I have checked that in my lab. 300MB is a new minimum value that is set during installation (although you can change it to 272 afterwards).