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Any way to use storage service like a system drive for VM and other pc? RRS feed

  • Question

  • I've got a bunch of little questions about azure storage:

    1) I read the D:\ drive on a virtual machine, temporary storage "may not be durable across reboots". I've rebooted the VM, and I find it comes up normally each time. Under what conditions is it not durable?

    2) Because D:\ isn't durable, I used the recommended approach to attach a disk and initialized it. So this disk is durable, but only as long as the Virtual Machine is running. 

    3) Then I made the even more durable "storage service" (aka blob) which is always on, and I can access it from anywhere. Within windows running on the VM I can use Azure Storage Explorer to use the files in the storage service. 

    So, then I wondered if there's any way to make the VM see the storage service as though it was a durable system disk? If so, it would allow me to unify a data storage for the vm and from any other browser. Is this possible in any way?

    Saturday, January 11, 2014 11:34 AM

All replies

  • hi Jeff,

    >>1) I read the D:\ drive on a virtual machine, temporary storage "may not be durable across reboots". I've rebooted the VM, and I find it comes up normally each time. Under what conditions is it not durable?

    About this issue, I want to correct a question. It is meaning that data may be disappeared not drive in the word---- "data on a resource disk may not be durable across reboots" . Each virtual machine that you create has a temporary local disk, which is labeled as the D drive. This disk is used by applications and processes running in the virtual machine for transient and temporary storage of data. It is also used to store page files for the operating system (http://msdn.microsoft.com/en-us/library/windowsazure/jj672979.aspx ).

    >>So, then I wondered if there's any way to make the VM see the storage service as though it was a durable system disk? If so, it would allow me to unify a data storage for the vm and from any other browser. Is this possible in any way?

    What is your meaning of "make the VM see the storage service as though it was a durable system disk" ? Did you want to see the attached disk in VM? If yes, you could initialize the new disk in you VM. For example, you could open "Server Manager", and selected "File and Storage Services", then click "Volumes" and select "Disks" and right- click your new disk, and then click "initialize" it. After do this, you will see the disk in your VM.

    Also, on my understanding, I think we could attach an existing disk on our VMs. At the same time, If we have other VMs, they could use it. Also we could use other storage explore tool to view it.  

    If I misunderstanding, please let me know free.

    Thanks.

    Regards,

    Will


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    Monday, January 13, 2014 6:28 AM
  • Hi, and thanks for trying to help with my question. I'm guessing that English might be a second language, so thanks also for trying to communicate. I think I need to clarify what you said.

    It is meaning that data may be disappeared not drive in the word

    I don't understand that part, but I do understand that the temporary drive holds temporary data like the page file. But it can also hold files that I save there, and I found these files continue even after I stop the server and restart it. So is there any risk I might loose a file that is saved on the temporary disk?

    For the second part, you understand that I want to access a drive that is outside the VM, and which two or more VM could access independently. I was wondering if I could use the storage service for this? (This is different than the attach disk procedure, where the disk is part of the server's VHD context, I think). I found I could access the storage service from the VM, if I use azure storage explorer, but I want to make that storage into something that the VM can access as an external disk. Can I do that? If so, how?

    Thursday, January 16, 2014 4:25 AM
  • I'm still learning a lot about Azure myself, but I'll answer these two questions to the best of my own personal knowledge:

    1) ...So is there any risk I might lose a file that is saved on the temporary disk?

    Yes, that risk definitely exists. Don't use the D drive for anything important because it might go away.

    2) ...I found I could access the storage service from the VM, if I use azure storage explorer, but I want to make that storage into something that the VM can access as an external disk. Can I do that? If so, how?

    If I understand your question properly, what you are asking for is not a directly supported scenario. This actually makes sense because the guest OS makes certain assumptions about the attached hard disks (such as, "I am the only machine that this disk is attached to.") Recall that the OS doesn't/shouldn't know it's running on virtualized hardware, so all the assumptions that it would make for a standalone system should remain valid in a virtualized system.

    Hope is not lost, however! Other workarounds may exist depending on what you're trying to accomplish. :) I came up with one workaround in a stackoverflow answer a while back that sets up a network share between cloud VMs, for example.  Once again, this makes sense because the Guest OS understands and assumes that a network share is a shared resource and can handle it appropriately.

    Good luck!

    Friday, January 17, 2014 8:50 PM
  • Thanks for confirming non-durability of files on temporary storage. As a side note, it seems strange that the default image for the VS 2013 developer VM includes such a huge (~250GB) temporary storage, which will mostly go unused and wasted. And one still wonders about the conditions that involve loosing those files, since as I discovered, over several restarts, the files remain as though they were durable.

    I looked at the stack overflow solution, and essentially it involved creating shares within a network of VM. That makes sense, but in my situation the shares are on the cloud, not within a network. I don't think this is an unsurmountable limitation, since we have the example of skydrive which allows system level file access from multiple computers on the cloud but not within a network. I guess the question might be refined to ask, if there are alternatives to azure storage explorer, that would allow me to see the same files through windows file explorer?

    Friday, January 17, 2014 9:09 PM
  • I'm not sure how putting the shares on the cloud invalidates the network share. I proposed that solution entirely using VMs running on Azure. No part of that answer touched a machine outside the cloud.

    Regarding the D drive, I ran across a blog post that pretty much answers your question. Paraphrasing:

    The os drive and data drives, are actually hosted in the cloud in Windows Azure Storage. This is how high availability is guaranteed.

    The D drive, on the other hand, is not actually hosted as part of windows azure storage. Rather, it's the physical storage that exists on the rack server which the VM is running on. If that physical disk dies, any information on it is lost precisely because it is a local disk designed for temporary storage that isn't backed up or stored anywhere else. The fact that any files you dropped have stayed there for you so far simply means that the disk hasn't failed and been swapped out. Yet.

    Thursday, January 23, 2014 11:07 PM
  • Hi Jeff,

    Do you still have  question on Azure storage?

    Friday, January 31, 2014 5:03 PM
  • That's very helpful. Thanks

    Saturday, February 1, 2014 10:00 AM
  • no thanks.

    Saturday, February 1, 2014 10:01 AM