New server setup/virtualization.

[teethdood]

What do you think about the setup below? Pretty solid or can I do better?

New server: No name Dell with 2-2TB drives running in RAID1 mirror. Ubuntu Linux running virtualbox with windows server 2003 or 2008 as GuestOS. (2003 has been kind to me. Any reason to switch to 2008?)
RAID1 safeguards against single hard drive failure. Virtualized windows server is a single file (that expands in size as needed). This makes it easy to simply copy that image every day to another machine as a backup. Would only take 2 minutes to install virtualbox and run the image as a server in case the main server dies. In addition, the file will be copied to external hard drives as well.
Ubuntu will also be setup as a web server for patient registration etc. in preparation for upcoming OD7.6 feature.
I can't think of anything else. Perhaps a fresh perspective from someone who's been there before. Thanks

[wjstarck]

If you're setting up a server from scratch, I'd rather see you running VMware ESXi 4.1 (free) with Windows 2003 or 2008 server and Ubuntu running as separate VMs.

My prior setup was VMware server running on Ubuntu 9.x - 10.4 and it was always flaky, and slow too (Granted this may have been a RAM problem as the box was 32 bit and therefore limited to 4 GB).

Windows Server 2008 is a nice improvement over 2003, it's more stable and faster too.

[teethdood]

Bill,

Thanks for your input. What do you recommend I run as the host OS? (you mentioned windows server 2008/linux as VMs) If I do windows server 2008 as Host, then I can't run another instance of 2008 as VM due to licensing issues. And the ease of having a single-file VM to backup and restore appeals greatly to me. What is your current setup right now? Thanks
Philip

[drtech]

I just tried ESXi 4.1 and it is rather picky on install, you have to have very specific hardware.

I also setup and ubuntu virtualization server running virtual box and that seems to be working great...only a test machine now, but it is FAST! Phenom II x6

[wjstarck]

What do you recommend I run as the host OS?

There isn't one.

ESXi is a little different than some of the others, as it's a true hypervisor. What that means is that it's kind of a low level OS that creates a hardware abstraction layer (HAL) for the virtual machines. So you would install ESXi, then install Windows as one guest OS, and Ubuntu as another. So you'd only need one copy of Windows.

What's nice about this is that performance is better, and the guest OSes are independent of one another. When I was running VMware server on Ubuntu, it was always a nuisance, because if I wanted to restart the Ubuntu box for any reason, I would either have to wait until lunch or after hours, because a restart of Ubuntu meant a restart of Windows, which would interfere with the ladies using OD.

David is right that it is much pickier about hardware, and the setup is going to be different than what you're used to with say, Windows or Ubuntu, so ulitmately it's going to depend on your experience/comfort level...

[Justin Shafer]

ESXi works great if you have the hardware. Since no OS why not buy 2 servers? Switch out the drives to the other server if hardware crashes. Backup your virtual machines. VirtualBox is supposed to be pretty fast and works well from what I hear. I have been wanting to use it with a cluster and DRBD for fun. But you dont really need too I could just use mysql and samba and to in on the application level. Or I could do what that one guy does with OpenFiler and make a redundant SAN and then have 2 other computers capable of being the server to the rest of the workstations... Requires manual failover for that one. We could just use VMWare Workstation.. It works... Not as hardware dependent and you dont have to mess with passthru usb. Or why not Full blown V-Sphere.. VMWares Clustering software.

All my clients just have a single server without virtualization and a minimum of raid.. some have a dell t310 with redundant power, raid, network teaming, and a dell remote access card.

What do you guys think?

[alkhaef]

Hey there guys...

I'm curious because I never considered any setups like these. I keep thinking about it, but I can't see any obvious advantages to doing any virtualization for an OD server. Other readers may be wondering too. Anyone care to enlighten me/us?

Thanks,

[teethdood]

I have since decided to go with my original plan of running Ubuntu Linux as HostOS, and win server 2008 as guestOS using virtualbox.

Here are the advantages:
* backup (part 1) in case server hardware literally burns up is going to be super easy. Simply copy the GuestOS (contained in 1 file called *.vdi) to wherever
* restore (part 1) is going to be super easy. Simply install virtualbox in another computer and run the backed up vdi file. Windows server 2008 boots up like normal.
* backup (part 2) using a virtualbox feature called Snapshots to make state-based copies of your vdi file. Superfast/small space to create snapshots. Have a disgruntled employee who messes with you by deleting some patient stuff? Go back to any point in time, pull out deleted information, go back to present, input back the deleted info. Fire the employee.
* restore (part 2) read above.

Here are the disadvantages:
* more complex to setup
* need a more beefy computer in terms of RAM in order to run 2 OSes. 4GB minimum, 8GB preferred
* if you need to reboot the HostOS for any reason, the GuestOS will be pulled down with it (thanks to wjstarck for pointing that out)

Virtualization is a very powerful thing

[alkhaef]

Hi Dr. Doan,

Thanks for your quick reply. Yes, virtualization is a powerful thing indeed .

I guess the big reason I first wanted to ask was that I myself have been looking for a way to address disaster recovery and fault tolerance simultaneously (and hopefully with less complexity than any alternatives).

If I'm understanding you clearly, disaster recovery with less complexity is the motivation, and virtualization (along with the approach you propose) clearly addresses that. It's a bit heavy, but snapshotting and backing up the WHOLE LIVE PARTITION ensures that the "OpenDentImages" is backed up in a consistent state with the database, along with the whole entire OS. That's pretty snazzy.

Have you given some thought to how to tie in fault tolerance with this approach? ...Meaning if the power supply, fan, memory, etc. goes bye-bye on the server during business hours, whether you can somehow continue to stay up and do business and then do the restore when it's more convenient? Hasn't happened to my server at the office yet, but it's still something I lose sleep over on occasion .

Best regards,
Al

PS, FYI, filesystems these days support native snapshotting (a couple under Linux, as well as NTFS under newer Windows Server releases). But taking advantage of those to the level you're suggesting could be arguably more complex than virtualization...

[teethdood]

Hi Al, always fun to have more ppl in the discussion.

As I mentioned in the post prior to your last one, I fully expect the server to literally burn up, kicked around, stolen, small SCUD missile going through the window and hitting it, etc. And that is perfectly ok, because I would have an image of the entire server OS in a file. I can then go to any computer in the network, install virtualbox (which is less than 100MB download) then load up the image. The entire process would take me less than 5 minutes downloading and installing virtualbox, pointing virtualbox to an external hard drive containing the OS image file, and back in business!

In case of a complete disaster such as a burglary and all the computers are stolen, I can bring in 2 laptops, one running virtualbox to boot up the server image, the other to use as an operatory computer to take X-rays etc.

The reason I'm so paranoid was in my older office, I had setup windows server 2003 in software RAID1 mode (mirroring). The primary hard drive failed, the secondary hard drive was ok. However, I could not make the secondary hard drive boot up. I lost a whole day, canceled all my patients, in order to get everything back up and running. I was already being really careful, what with the RAID1 and all, but still it was 1 day's worth of down time. I would rather have 5 minutes of down time, that's why I was looking into virtualization.

I know about ZFS and btrfs in Linux, but I didn't know about NTFS having snapshots too. Unfortunately ZFS is not in the kernel but in userland only, and btrfs isn't finalized yet, so I'm going to refrain for now.

[alkhaef]

Wow, Doc! I'm not used to seeing the words "userland" or "kernel" come from a Doctor... Something to be proud of .

Anyway, thanks for taking the time to help me understand your approach. I actually didn't know that virtualization software these days can do snapshotting. Your approach seems pretty cool, and I'm looking forward to hearing how it works out for you... Not that I'm hoping for you to have any disasters, of course.

Anyway, I hope the mini-SCUD doesn't hurt you or anybody in the office. Haha.

Best,

[JrGong]

There are different levels of snapshotting, one is at the virtual level and then the other can be done using logical volumes and the thrid is at the filesystem (this is of course not every option). Within a virtualized environment you can take a snapshot of the virtual machine, which is similiar to a backup but it records the exact state of the virtual machine (even what was resident in memory at the time). This is great for revision control etc but is very much like incremental backups and requires you to have the initial virtual machine to restore from.

When using most *nix based operating systems you have the option of creating 'logical volumes'. These are almost like virtual 'partitions'. You have a volume group that is assigned to a physical drive and within that volume group you create virtual 'partitions'. Then you format those logical volumes with whatever filesystem you please. The beauty is that you have the ability to do snapshotting along with dynamic resizing of those logical volumes.

I love virtualbox, but it is a Type 2 hypervisor, which isn't necessarily bad, there is just performance and scalability issues. Vmware ESX is a 'bare-metal' or Type 1 hypervisor (based off of RHEL). One of the biggest issues with ESX is that it does require specific hardware, it is enteprise level stuff, so they build it to work on a limited set of hardware to make sure its solid. Now that doesn't mean you are stuck using a Type 2 hypervisor, luckily there are 2 very powerful hypervisors that work with linux. The first is XEN which is a Type 1 hypervisor, it has been around a long tima nd is very stable and powerful, as well a feature packed. Some one was mentioning fault-tolerance, with Xen (and ESX) you can do live migration of virtual machines across physical machines, so you can move the virtual machine to another server without having to take it offline. Xen is supported by older linux kernels and has recently fallen out of favor. The reason being is that another hypervisor is currently mainlined (default, as in it is basically built into the kernel) into the linux kernel, KVM. KVM is arguably a Type 1or Type 2 hypervisor depending on how you look at it. If you are running Ubuntu I would give KVM a shot as it will definently give you a performance boost and supports a lot of nifty features like resource pooling and snapshotting.

....sorry for the book of a post.....