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Mounting an ISO file takes very long

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Kirill Müller

14 Aug, 2014 10:32 AM

Hi Feodor

As you suggested earlier, I've uploaded the files I need for building my projects to Azure, East US region. Furthermore, I have packaged all bits into a single ISO, with the intent to mount it to save on installation times. (No registry settings need to be applied.)

Downloading < 400 MB takes about 20 secs, which is acceptable, although I'd have expected it to be even faster. I think I can still compress the image for storage and decompress on the fly. However, the main issue is that mounting the ISO using Mount-DiskImage in PowerShell takes almost one minute! See an example build, and look for the progress indicators that begin with ==. (This used to be less when the image was still smaller.)

I can't replicate this on a fresh Windows 8.1 VM in VirtualBox.

Do you see a reason for this terrible delay? Is anything scanning the whole disk? Will a VHD be faster?

Thanks again.

Cheers

Kirill

1. Support Staff 1 Posted by Feodor Fitsner on 14 Aug, 2014 03:34 PM

   

   Hi Kirill,

   I've never tried both ISO and VHD and your experience here is very valuable. You should give VHD a try and see the how that works.

   For me bringing 400 MB of stuff for additional 1,5 minutes sounds great :)

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2. 2 Posted by Kirill Müller on 14 Aug, 2014 04:36 PM

   

   Thanks for the feedback. It's an extra effort to set up VHD, but doable.

   I just wanted to know if a virus scanner (or something else that scans the whole disk after mounting) is running on the build slaves. Without a remote desktop access to the slaves, it's difficult for me to find out. (Do you think it's possible to RDP into a running build session, perhaps after changing user password and adding permission? You haven't replied to my earlier post.)

   I think it's possible to cut the time required to a few seconds. Everyone would benefit.

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3. Support Staff 3 Posted by Feodor Fitsner on 14 Aug, 2014 04:57 PM

   

   It's a standard Windows Server 2012 R2 and it has Windows Defender on board: http://technet.microsoft.com/library/hh831778.aspx Whether it's ON or OFF - I will check that out.

   Regarding RDC - we especially put additional efforts towards making workers inaccessible from outside :) Maybe we could catch your VM while it's running and prevent it from being disposed after build?...

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4. 4 Posted by Kirill Müller on 14 Aug, 2014 06:18 PM

   

   Thanks, catching the VM sounds great, but how to manage it? The repo of interest is r-appveyor, I can open a branch for this exercise.

   If I wanted to create a VM in Azure that looks as similar as possible to the AppVeyor VM, which setting would you suggest?

   Something else occurred to me: Perhaps it is some form of auto-run that is enabled?

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5. 5 Posted by Kirill Müller on 14 Aug, 2014 07:33 PM

   

   I have now created a "tiny" A0 VM in Azure (Windows Server 2012 R2), mounting the ISO file in question using PowerShell takes only about 7 seconds there. Will investigate more.

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6. Support Staff 6 Posted by Feodor Fitsner on 14 Aug, 2014 07:36 PM

   

   Interesting. Keep me posted.

   - Feodor

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7. Support Staff 7 Posted by Feodor Fitsner on 14 Aug, 2014 07:41 PM

   

   I can give you an URL for AppVeyor image, but you should copy it to a storage in East US region to avoid traffic charges.

   - Feodor

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8. 8 Posted by Kirill Müller on 14 Aug, 2014 07:42 PM

   

   That would be marvelous, thanks. All my stuff is in East US now.

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9. Support Staff 9 Posted by Feodor Fitsner on 14 Aug, 2014 08:13 PM

   

   Great, will send it later today.

   - Feodor

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10. Support Staff 10 Posted by Feodor Fitsner on 15 Aug, 2014 02:41 AM

    

    Sent details by email.

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11. 11 Posted by Kirill Müller on 16 Aug, 2014 09:16 PM

    

    Perhaps a different path: Would it work to attach a VHD that is hosted in Azure directly to the virtual machine, via some Azure API?

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12. Support Staff 12 Posted by Feodor Fitsner on 16 Aug, 2014 09:26 PM

    

    Yeah, then VHD blob and disk should be on the same subscription with VMs.

    - Feodor

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13. Support Staff 13 Posted by Feodor Fitsner on 18 Aug, 2014 10:34 PM

    

    You can give Azure Files a try: http://blogs.msdn.com/b/windowsazurestorage/archive/2014/05/12/intr... Make sure your storage account is in East US region.

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14. 14 Posted by Kirill Müller on 26 Aug, 2014 10:14 PM

    

    FYI: Mounting a 500 MB-ish VHD also takes just over one minute.

    Unfortunately, I seem to need write access for at least some of the files, so I don't think Azure Files is an option currently. They aim at providing around 1000 IOPS, though, (and 60 MB/s for continuous reads), which means that in theory this can also work for lots of small files.

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15. Support Staff 15 Posted by Feodor Fitsner on 27 Aug, 2014 10:38 PM

    

    What code have you used to mount VHD?

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16. 16 Posted by Kirill Müller on 28 Aug, 2014 05:46 AM

    

    I'm using Mount-DiskImage -ImagePath $ImageFullPath in PowerShell.

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17. Support Staff 17 Posted by Feodor Fitsner on 28 Aug, 2014 11:33 PM

    

    OK, then we should live with that.

    I'll be experimenting with running builds with user profile loaded and we'll see if it makes any difference.

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18. 18 Posted by Kirill Müller on 29 Aug, 2014 07:42 AM

    

    Thanks. Please do let me know if I can do anything.

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19. Ilya Finkelshteyn closed this discussion on 25 Aug, 2018 01:47 AM.