How to make a backup virtual machine - linux

Can we use a virtual machine (Machine A) to take the backup of another virtual machines snapshot(Machine B). If we can do it what setup should we make (in machine A). Can you give me a working example with some real virtualization techniques.Assumption is that both the virtual machines are running on some cloud virtual machine management services for example like ovirt

Although it is a general question, I think the feature you are really looking for is snapshots.
I use a lot of cloud based VMs, most cloud provider offer you to snapshot your volumes, this is the preferred way to do backups in the cloud as it doesn't require you to stop or slow down your VM the back up is done at the disk level.
Later on you can restore your backups by creating an image out of your disk snapshots and spinning a new VM with this image.
On the other hand if you really need to backup a running at the filesystem level, you can have a look at rsync on linux/unix hosts. For Windows sorry I don't have a clue...

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Azure. How to Share Files Between Highly Available Web Servers

We have 2 Ubuntu VMs inside Virtual Machine Flexible Orchestration that are behind Application Gateway and are running Apache Tomcat web servers. When a client connects to one of the VMs and uploads the files that files also need to exist on another Virtual Machine.
I only found 2 options to do that:
Azure File Share - $80/month for 1 TB of Hot SKU, but the speed is only 1 MBs when mounted as SMB share on Ubuntu.
Azure NetApp Files - $600/month for 4 TB minimum.
Both of the options are not good, the first one is to slow and the second one is too expensive. What can we use in the development environment and production environment to achieve file sharing between Highly Available VMs?
1MBs is awfully low, I am not sure where this is coming from. I am fairly sure I get about 30MBs for Standard SSD/HDD deployments when mounting them into Linux docker containers, which should not perform worse.
An alternative to the mounted file shares would be to use shared disks. You can basically attach a disk to multiple VMs at the same time.
There are some limitations, for your case mainly mainly:
Shared disks can be attached to individual VMSS instances but can't be defined in the VMSS models or automatically deployed.
You can still expect to pay 50-200$ for the disk, but you should be able to get much better speeds than what you are currently getting.
Use a Blob and grant access via Managed Identity to your Virtual Machines:
https://learn.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/tutorial-vm-windows-access-storage
Blob Pricing and IOPS:
https://azure.microsoft.com/es-es/pricing/details/storage/page-blobs/

Azure virtual machines with shared premium disk - cannot see data

We've got two Windows Server 2019 virtual machines within the same Azure subscription and subnet. Recently, we have created a Premium SSD azure data disk with 'sharing' enabled and mounted it to those two VMs without any problems. It's perfectly fine to use the disk from both of the machines, but unfortunately files/folders added from one of them are not visible on the other.
Is it possible to somehow truly share the data between the machines using such azure disk attached to both of them? Maybe some super secret PowerShell option/flag when mounting the drives?
The machines are within same domain so obviously we can simply share a folder (which's what we do right now), but here the problem is that whenever our application is writing something to that share, it takes ages due to latencies/long upload times (effectively, it freezes the application for couple of minutes). Yes, they are in the same region (machines and disk). There's this Proximity Placement Groups thing available, but it does not seem to be applicable to disks, unfortunately.
We've also tried Azure Files but we've got exactly same problem as with 'shared folder' within the domain (long upload times whenever our application is writing something to the persistent storage).
I've went through Shared drive between Azure Virtual Machines but there's nothing about seeing the same contents from all machines which have the disk attached and mounted.
Thank you! Would appreciate any ideas.
Right so eventually I've found the answer. Basically the machines have to be joined into a failover cluster. Assuming the shared SSD:
is formatted to NTFS on both machines
has the same label on both machines (in my case F:)
if the conditions are met, that particular disk can be added to Cluster Shared Volumes. Program has no problems with writing the data smoothly from both machines.

Deploy a nodejs application on azure vm

I am trying to deploy a nodejs app on azure vm but I keep reading that the vm machine can crash or restart.
So lets say I opened the vm and installed nodejs and all the required tools I need then I get my code from github and started it, now every thing is running okay.
I am wondering what would happen if the vm restarted/crashed? Will the tools I downloaded and my code be lost? how can I make the vm when it start to redownload the tools, setup the environment, download my code then run it?
Azure Virtual Machines use Azure Blobs to back the OS disk VHD, as well as any attached data disk VHD. So, for those disks, everything is durable, regardless whether the VM is running or not (or crashes).
VMs also provide temporary storage on ephemeral disks. Assume anything placed on these temporary disks can, and will, disappear upon crash/restart.
So if you install any type of code libraries, apps, etc. on OS or attached disks, things remain in place unless you decommission the VM (and related storage), or delete it yourself.
Lots of documentation around Azure Virtual Machines and Storage, which can provide additional details.

Can you move/copy Azure virtual machines to a different instance?

If I setup a server running my application on an azure instance, for example A1 can I later change the instance to D2?
I might want to experiment with a VM at a lower cost but then move to a higher performing machine at a later date without having to rebuild everything.
Yes, you can change the size of Azure VM on demand. Changing the size will trigger a machine reboot and if you're using a configuration with SSD temporary drive, the content of the SSD will get erased. Other than that, everything else will be left untouched.
Drew, the Principal PM in this area has a great blog here about this.
You can only resize a VM to another offering that does not have fundamentally different hardware. Since A-Series and D-Series VMs have similar hardware, you would be able to swap those two around. You would not be able to go from A-Series to G-Series though. In addition you need to look at VM availability per region if you want to swap to something only in certain areas, as well as look at if you are using an ASM or ARM VM.
If you have an existing VM, you can check what it can swap out with in the new portal under "Size" in the VM Settings.
This will allow you to reboot into a different machine type, however any temp storage will be erased as with any VM reboot. You just need to ensure you are storing your persistent data in external storage.
You can learn more about the VM size offerings here.

Possible to keep two vhd's in sync on azure vm's

This is scenario than a specific technical question.
I have two azure vm's who run a web application in load balanced mode.
as per this article http://asheej.blogspot.in/2014/03/load-balancing-using-windows-azure.html
both virtual machines are attached an additional disk which stores images which are referred from web application hosted in vm's IIS.
Now What would be the best way to keep contents on two vm hard drives in sync.
For example, If i delete, add a data from vhd of first vm then that should also be affected on second vm.
Is there anything possible, probably using a common vhd for both machines which will take sync out of question.
Before going into solution , let me briefly touch base on the VM and disk relationship.
Typically a VM contains 3 Disks attached to them 1. OS Disk 2. Temporary Disk and 3.Data Disks. The VM will have lease on all these disks ,the only way to write into data disks is via the VM.
The C: Disk is persistent, meaning when the VM get rebooted the data in the disk is retained. But the D:\ is non persistent , when you reboot the disk will be fully wiped clean. So at any point in time the D:\ shouldn't be used to store any user data.
So writing a process to sync between two VM's just to keep pictures in sync is not very ideal. You might know this already , but wanted to set context for the choice of options provided below.
Your potential options are as follows
You can setup File Share using the new Azure File Service (In Preview) http://blogs.technet.com/b/uspartner_ts2team/archive/2014/06/09/setting-up-a-file-share-for-the-new-azure-file-service.aspx. This will be single source for all your images and you don't need to worry about syncing of files.
2.Store the images in the Azure Blob and access them from the application that's running in the VM http://blogs.msdn.com/b/yaohuang1/archive/2012/07/02/asp-net-web-api-and-azure-blob-storage.aspx and http://www.nickharris.net/2012/11/how-to-upload-an-image-to-windows-azure-storage-using-mobile-services/
3.Host another VM as a Webserver and host your images from there. Then the two VM's can refer the image. The cost here will be to hosting the VM.
The key point with all the 3 potential options there is no need sync the files in two different places , everything is in single place.
Edited based on new information:-
In your scenario hosting your files into VM is not the right approach. You should take the following into consideration even for the short term solution , if you are using Azure LB.
Azure Load Balancer uses a 5 tuple (source IP, source port, destination IP, destination port, protocol type) to calculate the hash that and map traffic to available servers and also the distribution is fairly random. So if you load balance the VM, you cannot control which VM the images are accessed.
Manual updates is not possible in this scenario.
You either need to setup an virtual network to allow you to create and share a windows file share OR you should investigate the use of Azure File Service for creating a share that both VMs connect to (see: http://blogs.technet.com/b/uspartner_ts2team/archive/2014/06/09/setting-up-a-file-share-for-the-new-azure-file-service.aspx).

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