Unfortunately the 1GB overhead is hard set and can not be changed (as a user configurable setting anyway).
As for ZFS, I’m not aware of any accurate algorithm for determining RAM requirements/utilisation given some parameters. At an absolute minimum you require 1GB for ZFS to function without risking major issues. In your scenario, I would be investigating either adding more RAM to your box (doubling it might not be a bad idea) or seeing if anything that your running can be moved to a native or LX zone. In case you aren’t aware, zones do not lock down their memory assignment on startup and simply have a cap. - Dave On 7 Jul 2015, at 10:26 PM, Schmurfy <[email protected]<mailto:[email protected]>> wrote: Thanks, this explains everything xD is there a way to tweak this 1GB number ? I don't get what this reserve is actually used for since from inside the VM I only see what I allocated, is it for the qemu process itself ? For ZFS how much memory should I give it and what it depends on ? I tried to find more information on this but I have yet to find a useable formula to give me a precise idea. On 7 July 2015 at 12:38, David Finster <[email protected]<mailto:[email protected]>> wrote: For KVM based virtual machines, SmartOS will reserve <ram amount> + 1GB as soon as the VM is started. The additional 1GB is to manage any potential temporary overruns inside QEMU/KVM. So based on that, you actually created 4 x 3.5GB VMs which would require 14GB. Keep in mind that ZFS relies on having a decent amount of RAM available for it to function correctly - you don’t want to get into a situation where a system has no free RAM (RAM used for ARC cache is free-able). You can normally see if your hitting RAM availability problems by starting the VM and going into /zones/<uuid>/root/tmp/vm.startvm.log. There you will likely see the progress of locking memory. To make the best use of your resources, you should look towards either native ‘joyent’ brand or ‘LX’ brand zones instead of KVM. Joyent zones are the SmartMachines you get on Joyent Public Cloud and are a pretty friendly UNIX environment to work with. LX zones on the other hand emulate a Linux kernel, are newish and are quite a significant development focus at the moment. - Dave On 7 Jul 2015, at 7:55 PM, Schmurfy <[email protected]<mailto:[email protected]>> wrote: Hi, I was wondering if there is a way to know how much memory I can use for my VMs, until now I am almost blind and sometimes it work sometimes it doesn't. Yesterday I tried to create 4 VMs with each 2.5 GB on a 16GB host and the last one failed to provision, I had to reduce its memory to 2GB to make it work, without that the VM was shown as runnning but was really not: "vmadm info" hanged, no network up, "vmadm console "did nothing. In this case sometimes I see the provisioning of the VM failed (as shown in vmadm list) and other times it appears to work but the VM is in a hald dead state like above. We are a small company and we would really like to use as much as possible our current hardware resources, that's why I am looking for a way to estimate what ZFS and the host need/use. smartos-discuss | Archives<https://www.listbox.com/member/archive/184463/=now> [https://www.listbox.com/images/feed-icon-10x10.jpg10f3ec5.jpg?uri=aHR0cHM6Ly93d3cubGlzdGJveC5jb20vaW1hZ2VzL2ZlZWQtaWNvbi0xMHgxMC5qcGc] <https://www.listbox.com/member/archive/rss/184463/25738179-216c4b5f> | Modify<https://www.listbox.com/member/?&;> Your Subscription [https://www.listbox.com/images/listbox-logo-small.png10f3ec5.png?uri=aHR0cHM6Ly93d3cubGlzdGJveC5jb20vaW1hZ2VzL2xpc3Rib3gtbG9nby1zbWFsbC5wbmc] <http://www.listbox.com/> ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
