Degrees's Journal: How to add RAM to a server so nobody notices: virtualize

Yesterday I noticed that my GroupWise mailbox was snappier. Didn't know why, and thought that maybe the email archiving software had trimmed my mailbox (which would be a good thing). I've got 19 GB in my mailbox, and 18 GB of it ought to relegated to the archive. Nope - turns out my co-worker had added RAM to the server while nobody was watching.

GroupWise has a mode called Client/Server where your desktop fat client talks to the server via TCP/IP packets. Back around GroupWise 5, if the post office agent (on the server) went down at all, everyone knew it because every machine immediately got an error on the screen: lost contact with server! Somewhere around GroupWise 6 or 6.5, Novell reprogrammed the fat client to wait instead of immediately throwing up an error. The timeout is about 30 seconds.

Last year we started a whole push to virtualize as much as we can. We use Xen virtualization, as that is what Novell supports and includes in SuSE. Paravirtualization has a few advantages, one of which is that you are essentially running a guest OS that is the same as the host OS. So when it comes time to reboot, the OS is already loaded in RAM - the Xen host just has to create the guest, and do a bit of linking. We typically see an init 6 take ten seconds from time we lose continuous ping packets to the time we get them back.

My co-worker was looking at the server stats, and the mail server showed pretty much 100% utilization 24 x 7. Certainly the post office seemed slow. He thought it might be a process gone bad, but no - the mail server was just that busy. It looked like it could use a little more RAM though.

(Prepare by opening the Virtual Machine Manager)

Init 0
Edit the VM definition to have another 1 GB RAM
Init 3

It is up, and before the 30 second timeout from 120 fat clients. Nobody notices, nobody calls. It just works (and faster, too).

Sweet. :-)

Sweet indeed

[jawtheshark]

Nothing more to say, that is just cool.

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[Degrees]

Thanks.

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[Kymermosst]

You want to know what's cooler? You can add memory or VCPUs to a Sun LDOM (on T1/T2 CPUs) and don't even have to reboot the VM. The guest Solaris instance sees the memory or VCPU and makes it available. This stems, of course, from the capability of being able to add or remove physical system boards to/from the bigger boxes while the machine is running.

When do we get dynamic reconfiguration and hotplug CPUs/Memory in the x86 world???? I should seriously be able to add VCPUs or memory to a virtual machin

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[Degrees]

That is pretty cool. Probably took some significant engineering to get to work right.

Gotta love virtualization

[Sylver Dragon]

I've been running VMWare at work now for slightly over a year and love the freedom it gives me. Granted, I'm a bit superstitious about putting my email and database into VM's; but, a large part of our infrastructure has been virtualized out.

I'm even starting to research the idea of desktop and application virtualization to get the OS untied from the hardware and the applications untied from the OS. After seeing a demo in which Photoshop was run from a thumbdrive, without an installer, I'm hooked.

If y

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[Degrees]

We do have one or two VMWare ESX servers running. Primarily due to cost, we're doing Xen virtualization instead. I know there are free versions of VMWare now, but we wouldn't necessarily get any support from VMWare / Citrx.

The whole idea behind XenApp and XenDesktop is something we are looking at. We may go with a more traditional PXE boot + ZENworks re-imaged workstation plan though. We don't have a huge need for mobile solutions, and can lock things down pretty tight with ZENworks. Another option is th