ESXi snapshot newbie question

[TeeJayHoward]

While creating a snapshot of a VM, can you continue using the VM? I only ask because it seems to take about 15 minutes to make a snapshot, and I like to have multiple snapshots for each VM... If I have to wait 15 minutes between each, it's gonna take all day to configure a single server.

Example:
Fresh install
Snapshot
Windows Updates and basic configuration
Snapshot
Programs/Roles install
Snapshot
Programs/Roles configuration
Snapshot

That's an hour in snapshotting alone... I did notice that I can still use the VM, but will it screw with the snapshot if I do? For example, if I just finished a fresh install, click the "Take Snapshot" menu item, and immediately start downloading and installing Windows Updates, will the snapshot be of the VM prior to the updates, somewhere during, or after?

 

[ashman]

Sounds like you are a little paranoid with respect to the stability of you VM's. Do you have a backup solution in mind for your VM's? You might want to look at software such as Veeam or VRanger for VM backups. I say this because snapshots are only meant to be used before you make a critical change to a VM, for example, installing a service pack, otherwise there is no real need to take snapshots, in fact it can be a very bad thing as they accumulate and grow, if you don't delete them. In your example I see no need to take one snapshot at all. However, once you were done, you would certainly want to make a backup of your VM, perhaps even a template if you are going to build similar VM's. You don't mention what Hypervisor software you are using, not that it matters, although the backup software I mentioned works with VMWare and Microsoft.

In answer to your question, as soon as you hit the snapshot button, the OS is frozen at that point in time, whatever you do afterwards would not be contained in the snapshot.

 

[TeeJayHoward]

Sounds like you are a little paranoid with respect to the stability of you VM's.

Not stability. I just like being able to backtrack easily.

Do you have a backup solution in mind for your VM's?

Yes, my entire datastore is backed up to an external USB drive once a day.

In your example I see no need to take one snapshot at all.

What if the Windows Update borks the install? I've had it happen on bare metal. No reason to believe it won't happen in a VM. What if I install the wrong role by accident because I'm not paying attention to which window I'm typing in? Sure, I could just uninstall it, but reverting to a snapshot makes more sense. That way, I don't have to wonder if tidbits are left behind. Or how about if I want to set up a role and use the VM as a template? I'd want a snapshot of it before I configured it.

You don't mention what Hypervisor software you are using, not that it matters, although the backup software I mentioned works with VMWare and Microsoft.

The title of the thread mentions the hypervisor I'm using . Specifically, it's ESXi 5.0.0.

In answer to your question, as soon as you hit the snapshot button, the OS is frozen at that point in time, whatever you do afterwards would not be contained in the snapshot.

Glad to hear it. I was debating creating a snapshot with notepad open, and starting to type immediately after I pressed the "Take snapshot" menu item. If it works the way you mentioned, then nothing I typed would show up in the snapshot.

I have a hard time understanding how it saves the current state of the machine in such a short period of time. If the VM had 128GB of memory allocated to it, wouldn't it need to save all 128GB to the datastore before you could make a change? Modern hard drives are fast, but they're not 128GB/s fast.

 

[Vader]

Firstly, snapshots should be used sparingly. There was a post here the other day that explained use cases of snapshots and the limitations and problems that could occurr if not managed/utilized properly. Please refer to this post:

http://hardforum.com/showthread.php?t=1682986

What should be done, in your case, is after the fresh install and latest updates at that time, you should build a Template. Roll out from your template and only use snapshots at the next change cycle, IE Updates, Application rollouts..etc, however, those snapshots should only be kept for a brief period of time as to not grow into an issue down the road. Validation should be done after the change, then the snapshot should be deleted after validation.

Don't get me wrong, snapshots have their place and work great, however, they should be used properly.

 

[Child of Wonder]

Do not use snapshots in the manner you're suggesting. They're not a backup, they're just a transaction log or delta of every write IO that would have occurred to the VM. As time goes by, that delta gets bigger and bigger and bigger and if left unchecked could even fill the entire datastore it resides on which would cause every VM living there with it to go down and possibly become corrupted.

Assuming you're using vCenter, create a single VM, call it "Windows <version> Template." Install and configure Windows on it per your company's best practices. Put any mandatory software you need on it (AV, etc.) and install all the latest Windows Updates.

Then power down the VM and "Convert to Template."

You can also create a Customization Script from the home page of the vSphere client so when you deploy a new VM from the template it will automatically join your domain, get an IP, etc.

Otherwise, I'd highly recommend learning Microsoft MDT. That also works great for deploying VMs since you can simply create a new VM, PXE boot it, and then select the exact Windows OS, apps, and settings you want applied and it will all install over the network.

 

[lopoetve]

What Child of Wonder said.

Effectively, "welcome to the number one mistake people make with snapshots. It's not a backup".

 

[TeeJayHoward]

I'm trying to "make do" with only two computers right now, and I must say, it's becoming a big pain in the ass. I told myself I wouldn't build another host until Ivy Bridge got released. Today I tried to work with templates, since it seems like I'm misusing Snapshots . Turns out, vSphere client lacks the ability to create a template. I had to download and install an evaluation copy of vSphere server. Well, Server doesn't work on a Server 2K8 Core install (VM1), or a Domain Controller (VM2)... So I had to install it on my desktop... My workstation is now my NFS server, my vSphere Server, my IPMI viewer, and probably a dozen other roles I've forgotten about. Anyway, this wonky setup is causing a few... uhm... hickups. I've noticed that if I reboot my workstation/file server, ESXi loses track of what VM is where, and I have to recreate the VM. I can point it at the existing virtual disk, so no data is lost, but it's kind of a pain... Is this just because ESXi can't find the NFS share?

 

[lopoetve]

yep. It should clear up a after it comes back for a bit.