Possible bug in simultaneous users on a project

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Possible bug in simultaneous users on a project

Unread postby Rob Davis » Wed Jun 19, 2019 10:13 am

HI
We have three users each with professional licences, working on our projects.
Most of our projects are located on a shared network drive so that anyone can access any project.
We have relied on the 'lockout' which meant that if one of us has a topic open, then anyone else accessing the same topic would get a red banner at the top of the screen saying that the topic was open elsewhere, and preventing the second user from making changes. (At the topic level - we could still open other topics and work on them).
Today - while discussing a project, two of us had the same .hmxp project open - and we did not get the warning, and we could both update the open topic.
Why did we not get a lockout?
Is this a bug?
Rob
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Re: Possible bug in simultaneous users on a project

Unread postby Tim Green » Wed Jun 19, 2019 10:50 am

Hi Rob,

The most common scenario where this can happen is if you have Windows running on a virtual machine and the project is on a drive outside the virtual machine. This applies particularly and especially if it is a Parallels virtual machine, but we have also seen it on other scenarios. What happens is that the Windows file locking information is not transmitted properly when the files are accessed across the VM boundaries. This is generally fine for normal applications but can cause problems when you need to control shared access to files as in multi-user editing of Help+Manual projects.

If you ever experience what you describe, i.e. that two users are both able to edit and save the same topic at the same time, it means that the configuration is not currently secure for multi-user editing because the necessary sharing information is not available. As far as each Help+Manual client is concerned, nobody else is editing the project because they can't see them.
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Tim (EC Software Documentation & User Support)

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Re: Possible bug in simultaneous users on a project

Unread postby Rob Davis » Wed Jun 19, 2019 12:19 pm

Yup - that's it! The shared drive runs on a VM and we each have our own workstations.
Not much we can do about it given our present setup - we are going to have to just control it the old fashioned way - talking to each other!
Not ideal, but I don't see an alternative in the short term.
Thanks for the quick turn-around.
Rob
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Re: Possible bug in simultaneous users on a project

Unread postby Tim Frost » Wed Jun 19, 2019 9:16 pm

Tim, is this something that is more of a problem with typical H&M usage, or are you suggesting it is a general problem? If the latter, do you have any links to technical descriptions of the issue with VM boundaries? We have customers who share many thousands of small files, locked and unlocked across multiple machines and across VM boundaries, without having encountered any VM-specific problems.

The one thing that you do have to be concerned about is if any of the operating systems have directory caching enabled (which is the default on newer OS) and others do not, and particularly with a mix of SMB1 and SMB2. There are three registry keys you can add with zero values to disable this caching (which causes network machines not to see updated files and locks), whether or not VMs are involved. They are described at http://technet.microsoft.com/en-us/library/ff686200(v=ws.10).aspx.
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Re: Possible bug in simultaneous users on a project

Unread postby Tim Green » Thu Jun 20, 2019 7:38 am

Hi Tim,

To date this has simply been empirical. The worst culprit has been Parallels on the Mac, although I haven't seen any recent reports on this so I'm not sure what the current status is. In the past, if Windows was running under Parallels on a Mac it was not possible to do local multi-user editing of HM projects that were on a network share outside the Parallels VM, because all users would see that they were the only ones accessing the files.

Your information on those registry keys is interesting, I'm passing it on to our developers responsible for the multi-user components for consideration. 8)
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Tim (EC Software Documentation & User Support)

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Re: Possible bug in simultaneous users on a project

Unread postby Tim Green » Fri Jun 21, 2019 11:36 am

Update: I just had an interesting discussion about this with Michael Schwarzl, our crack networking and VM expert.

@Rob: One possibility in your case is that the VM on which your file share is hosted is running an older operating system or possibly even a Windows Home version. If that is the case it could still be serving out the shares with SMB1. If you are on the current version of Windows 10 on the machines you are working on, it has now completely disabled SMB1 and only has SMB2. You would then be communicating between SMB2 and SMB1, which is problematic, as Tim Frost points out, and could definitely cause loss of the file locking information you need for multi-user.

Michael also wanted me to emphasize that nobody should ever use Windows Home on a network, under any circumstances. It is not just that things like domains aren't supported. In addition to that normal networking is restricted in ways that are not well defined, and you can frequently experience all kinds of strange problems that won't happen if you are using Windows Professional. Bottom line: Windows Home is really for home computers that aren't connected to networks. 8)
Regards,
Tim (EC Software Documentation & User Support)

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Re: Possible bug in simultaneous users on a project

Unread postby Rob Davis » Sun Jun 23, 2019 10:01 am

Thanks for the followup message.
As I said, we are using VMs (and are in the process of upgrades/changes to support an office relocation (fun, fun, fun). )
I am pretty sure we are NOT using Windows Home on any of our laptops or workstations.

But bottom line is that we rely heavily on the ability to have the projects on a server and several people work (from office or from home - on Windows10 laptops).
We might be adding a layer of complexity because we have two domains - but that's all black magic to me

I will try to discuss this thread with our IT manager (when he gets his head out of the purchase catalog for the stuff we need in the new office!)

Rob
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