Virtualization Host

[tarciosaraiva]

Hi guys,
this is my first post - yay - and I'm not even sure if I'm posting in the right forum, but here I go.

I have some servers with Ubuntu on them. They are hosts for VM's and I'm using the VM's to provide some services. That's all fine.

My question is: can I use the host to do something else as well?

I mean, of course it depends on the amount of memory the guests are consuming and all, but . . what could I use for? Storage? Authentication?

Thank you guys!

[tarciosaraiva]

Anyone?

[monday90]

OK first off virtualisation is quite disk intensive. Unless your servers are in a multi disk arrangement and you have spare capacity I would rule out anything like a fileserver. Authentication is a possibility so long as the load is fairly low. You could consider running it as a basic web server, again as long as the load isn't too high.

Without knowing the specs of your server and the demands placed on it by the VM's its difficult to say. If its a little dualcore thing with 2GB ram and a couple of SATA drives running a few VM's for a small office then you are probably running close to your limits. If on the other hand you have some kind of 4xQuad core monster with 40GB of ram and enough hard disks to build a bungalow then the odds are you will have a fair bit of spare capacity and it could probably do anything you needed.

[tarciosaraiva]

OK first off virtualisation is quite disk intensive. Unless your servers are in a multi disk arrangement and you have spare capacity I would rule out anything like a fileserver. Authentication is a possibility so long as the load is fairly low. You could consider running it as a basic web server, again as long as the load isn't too high.

Without knowing the specs of your server and the demands placed on it by the VM's its difficult to say. If its a little dualcore thing with 2GB ram and a couple of SATA drives running a few VM's for a small office then you are probably running close to your limits. If on the other hand you have some kind of 4xQuad core monster with 40GB of ram and enough hard disks to build a bungalow then the odds are you will have a fair bit of spare capacity and it could probably do anything you needed.

That's what I thought. I can't really do much as my servers have only 8 GB RAM
Plenty of disk space, but not enough memory.

Thank your for your reply

[monday90]

8 Gig is a reasonable amount of memory, are you running a 64bit system? How many Vm's are you running and what sort of load do they have? I normally work on the basis of one hdd per virtual machine (on important systems two as I mirror them). I normally figure that the host machine should be stripped to a bare minimum and left to look after the Vm's. Anything else you virtualise. There is nothing stopping you running multiple services on a single Vm as long as you think it through.

[tarciosaraiva]

8 Gig is a reasonable amount of memory, are you running a 64bit system? How many Vm's are you running and what sort of load do they have? I normally work on the basis of one hdd per virtual machine (on important systems two as I mirror them). I normally figure that the host machine should be stripped to a bare minimum and left to look after the Vm's. Anything else you virtualise. There is nothing stopping you running multiple services on a single Vm as long as you think it through.

Hi there. My HOST OS is 64 bit, yes. The VM's are 32 bit.
I have two hosts - both with 8 GB RAM, but one has 300 GB HD.

The host with 300 GB has 3 VM's running, consuming 64% of the memory and not even 20% of disk space.

The other got 83% of memory usage but that's very likely to go down as I'll be destroying some VM's not needed anymore.

I believe if I shuffle some things I'll be able to manage it pretty well. One of the VM'S got 3 GB RAM assigned to it - it's a DB server - but I think it's too much.

Anyways, this is the picture Thanx again!

[monday90]

How many hard disks do you have? The purchase of extra may well solve your problems. A 32 bit os can't address more than 2GB of ram (well not without a bit of tweaking). If all of this is running on one hdd try getting another and moving one (or more) Vm's to it. the hdd is a bottleneck in most systems, if you are running four (host + 3xVm's) then everything will slow to a crawl. Keep your host minimal, you don't need any office suites or games on it. If you are running Virtualbox you don't even need a desktop. your host should be running comfortably with 512MB ram. Each VM could then have 4 Vm's each running with 1920MB ram each. I have a fairly old dualcore laptop with 4 gigs of ram. I have virtualised a small windows forest on it before consisting of 6 Vm's. this connected to a network where a further 8 servers attached to it. It ran very hot for three days until I could migrate to new hardware.

[tarciosaraiva]

How many hard disks do you have? The purchase of extra may well solve your problems. A 32 bit os can't address more than 2GB of ram (well not without a bit of tweaking). If all of this is running on one hdd try getting another and moving one (or more) Vm's to it. the hdd is a bottleneck in most systems, if you are running four (host + 3xVm's) then everything will slow to a crawl. Keep your host minimal, you don't need any office suites or games on it. If you are running Virtualbox you don't even need a desktop. your host should be running comfortably with 512MB ram. Each VM could then have 4 Vm's each running with 1920MB ram each. I have a fairly old dualcore laptop with 4 gigs of ram. I have virtualised a small windows forest on it before consisting of 6 Vm's. this connected to a network where a further 8 servers attached to it. It ran very hot for three days until I could migrate to new hardware.

I have 5 hard disks. Raided and LVM'd on the host. I'm running KVM + QEMU.
I believe, based on what you mentioned, I need to shuffle some things around to get what I need.

Thank you for your answers

[monday90]

Instead of LVM and RAID on all your disks, consider devoting those machines with less hard disk requirements to a single disk. if needs be mirror it to a partition on another disk. this will cut your write times in half. An 8 gig system with 5 hdds should run like its on fire. Believe it or not but running RAID on the host will actually slow your guest machines down.