Network Shares and Multiple Users

Are they logging in with the same username?

Same IP address may cause the same problem.

What do you mean about the ip problem? I can see if to users are sharing the same IP you will have problems. It doesn't matter what OS or network -- you must have different IP addresses.

Are you saying both users are logging into the same machine at the same time, if so they you are correct the second user will not be able to access the share even though the permissions are correct

this is because although they are in the same group, they actually log into the share with their usernames, so when user one logs in they mount the share with their credentials, so if user two logs in at the same time they can't access the share.

Is there any reason you need 2 users logged in at the same time?

I guess you could unmount the share then reconnect to it, this might be scriptable too

It may depend on the version of OS X being used but the following worked for me and may describe something that will help you.

As others here have indicated, normally you can only have once user logged in to a file server from a Mac at a time, or at least only one user that works properly. This restriction historically has applied to network login accounts and network home directories rather than a group share or a general file share. Obviously if you can't have two network logins at the same time on the same Mac, the issue of then not being able to access the same group share or general file share is not one you hit because you are blocked before that stage.

This is down to the way network shares are mounted and accessed by accounts. Normally when a network login account is used the first (and only) network login mounts their network home directory on to the client computer in the /Volumes directory. This mount is 'owned' by the user logging in and that specific mount is therefore not accessible by other users on that client Mac. What makes things particularly problematic for network home directories is that Open Directory is set to use a specific path for a user network home directory. Which leads us on to the second issue...

It is hypothetically possible to have two different users logged in on a client Mac, and have each login to the same share. If this is done, the second user cannot use the first users mount point because it is 'owned' by the first user, and the automount system will mount the share under a different path so you might end up with the following

User1 = /Volumes/FileServer

User2 = /Volumes/FileServer-1

even though they are both accessing the same share on the same server which has the same name. As mentioned above in the case of network home directories which have to be accessed via the path defined in Open Directory User2 will fail because their version of the path is different to what Open Directory says, and if they try using the path from User1 they are denied access. However for a general file share the actual path is less important in most cases so theoretically the user could go to /Volumes/FileServer-1 and access files successfully.

The real-world instance I had a similar setup that worked was as follows. I had a Mac XServe running as a Terminal Server using iRAPP. Users connected to the XServe via Microsoft Remote Desktop Client and logged in as network login accounts. I used NFS for the network home directories which avoided the issues above. However these users all still wanted to access a Mac FileServer (a different XServe) via AFP. This worked but as mentioned above each user got their version mounted with a different name. If I had five users logged in then I would have the following mounts

/Volumes/FileServer

/Volumes/FileServer-1

/Volumes/FileServer-2

/Volumes/FileServer-3

/Volumes/FileServer-4

Each of these showed up on each users desktop (via Microsoft Remote Desktop) and they could only access in the Finder their own. If I was using an Application that was using a specific file path it would potentially get confused as to which version to use, in my case this was an AppleScript but I worked round it by testing (in a loop) which version allowed access to a file without error and then knew that path was the correct one.

In conclusion you might be able to have multiple users access the same share via AFP from the same server but may find that you need to access it in a slightly different way.

that approach could cause issues for some types of file, I realise they said it was for medical but if any files relys on linked files these will break because of the change in file path, for instance if it was a design agency using In Design you would have missing links if you reopen the file at a later date.

This might not be an issue in this case

I tried on my computer to log into my MacMini Server with OSX 10.8.2 and it's letting me log on to it from different user accounts at the same time as another account is logged in and that includes Windows running in Virtualbox and guest account and the main account. None of them are limited at all other than permissions on the guest account but it still has access just limited. I'm not really sure what is going on with yours.

It is not a deficiency in MacOS at all. This situation exists because of the way the AFP protocol itself works. While it is technically possible to share out files using NFS or HTTPS, these are not simple things to do for a layman and require some skill at the Terminal.

What are the practical reasons for different users wanting to use the same systems at the same times? I recommend having the users stick to their own systems. If different users have different access it is better from a legal HIPAA compliance perspective. If people are sharing systems due to cost, you might look at a lower-cost solution like a Mac mini with $100 Acer monitors.