gurdon

Q: Sync OS X Servers in different locations - how?

Hi everyone, this is my first post.

I help to run an office of Macs and we are looking to expand.

We have a Mac mini running OS X Server that controls 10 Mac Pros. User data is stored on this server. We are looking to open another office with slow (ADSL) connection and would like a similar setup: several Mac Pros and OS X Server with storage.

Staff can use any machine and would be expected to travel between the two offices. As a result we need to facilitate access to users' data from each office - this is why syncing OS X Servers would be ideal.

There are no databases or bespoke apps - user data consists of documents and larger video files.

Is it possible to implement this setup? What is the best way to link multiple locations into one network?

Kind Regards,
Ian

Posted on Mar 31, 2016 11:05 AM

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Q: Sync OS X Servers in different locations - how?

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  • by Strontium90,

    Strontium90 Strontium90 Mar 31, 2016 4:34 PM in response to gurdon
    Level 5 (4,077 points)
    Servers Enterprise
    Mar 31, 2016 4:34 PM in response to gurdon

    I will get the discussion started.

     

    So, on the surface, OS X Server has a number of features to allow you to unify the two locations.  Let's make some assumptions.  First, you will have a firewall installed at each location that allows persistent site to site VPN.  Now, you have one large network in two physical locations.  This means that users in site A can access resources in site B and vice versa.  Ok, that takes care of the network.  That is outside OS X.  Next, the user domain.  Open Directory supports master and replica structures.  You can define one server to be the domain master and another (or more) to be a replica (or replica of a replica).  Now, you have a centralized location for users, groups, passwords, policy, etc.  This is all built on a solid DNS infrastructure which also supports master/slave configuration.

     

    Ah, so on the surface, this means that users can move between locations and use the same core domain services.  But, you hint at the ability to "Staff can use any machine and would be expected to travel between the two offices."  This presents an interesting challenge.  In OD, a user can be assigned a network home folder, allowing the user to use any machine and access a home folder from a network location.  This allows the user to access any machine and always have access to her data.  Ah, but OD defines the home folder as a single value.  So, user Ian might have a home folder pointing to serverone.gurdon.com.  But is serverone is in location A and user Ian goes to location B, his login time will be really slow since he needs to traverse the ADSL line to access his data.  Basically, it will be unusable.

     

    So, perhaps a better solution is to not link the servers via OD but to create exact copies on both sides and only sync the data.  Here is my thinking on this.

     

    Site A:

         Server named sitea.gurdon.com

         Users: John with UID 1026, Mary with UID 1027, Bobby with UID 1028, and Sue with UID 1029

         Users all setup to access a local network home share on sitea.gurdon.com, allowing John, Mary, Bobby, and Sue to move access their home from any system.

     

    Site B:

         Server named siteb.gurdon.com

         Users:  John with UID 1026, Mary with UID 1027, Bobby with UID 1028, and Sue with UID 1029

         sers all setup to access a local network home share on siteb.gurdon.com, allowing John, Mary, Bobby, and Sue to move access their home from any system.

     

    In the background:

          You use a synchronization product to two way sync user data between the two locations.  As long as your UID/GUID values are the same, then the two systems will run independent of each other as two distinct yet matching OD servers.  To sync the data, look at something like File Replication Pro, GoodSync, or rsync.  Depending on the user behavior, you might be able to do a nighty sync instead of a live sync as the assumption will be that users will spend a full day at one location and not move between locations within a workday.  That ADSL is you roadblock. 

     

    Ah, now the pieces of this that will make it all fall apart is the mention of " user data consists of documents and larger video files."  Network home folders and video workflows is like oil and water.  Generally it is something you can setup but the experience is a goopy mess.

     

    Now, there is also the possibility of products like DropBox, allowing user data to cache to a cloud solution.  Or, perhaps you centralize you work on the file server and then just sync file server data, allow the clients to be thin.  If you go with network home folders you must be at minimum on a 1000Base network.  I recommend the server be link aggregated or you move to 10gigE.

     

    I think the overall statement is that this is a problem that has a solution.  However, more details about your workflow are required to fully expose the best possible solution.

     

    Hope this helps with the thinking process.

     

    Reid

    Apple Consultants Network

    Author - "El Capitan Server – Foundation Services"

    Author - "El Capitan Server – Control & Collaboration"

    Author - "El Capitan Server – Advanced Services"

    :: Exclusively available in Apple's iBooks Store

  • by John Lockwood,

    John Lockwood John Lockwood Apr 1, 2016 2:14 AM in response to gurdon
    Level 6 (9,309 points)
    Servers Enterprise
    Apr 1, 2016 2:14 AM in response to gurdon

    Open Directory itself will be easy as you can create a replica server to run at the second site. In theory you could use something like rsync or other syncing tool to sync the files on two servers, however the big risk here is that if files are in use they may not sync intact.

     

    If your using network home directories then you cannot realistically sync this because the file paths would be different and the user account will not use the local server at the opposite site. So using mobile accounts where the home directory is stored on the users laptop is the best option.

     

    Your biggest issue is going to be network speed. I would hope your main office has a leased line of some sort rather than ADSL but if your main office has ADSL like your second office does then you will have the same problem its end. That is ADSL as its name says is asymmetric it can download faster than it can upload. So lets say your main office does have a symmetrical leased line then it can send fast and the second office can receive (download) fast, but the second office can only send/upload much more slowly, so slow that it may be impractical to do any syncing.

     

    I don't think it will be suitable for you but Microsoft Servers have a function built-in called DFS which is specifically designed to allow a branch office to have a local copy of a main office file server, this would require having Windows servers at both sites and you would still have the issue over ADSL slow upload speeds.

     

    Note: The Finder on the Mac is particularly bad at coping with a slow (remote) link to a file server.

  • by cdhw,

    cdhw cdhw Apr 1, 2016 3:24 AM in response to gurdon
    Level 4 (2,653 points)
    Servers Enterprise
    Apr 1, 2016 3:24 AM in response to gurdon

    I would urge you to get a proper business-grade network connection and solution.


    If you're stuck with ADSL you might be better off using VNC rather than trying to sync file servers. Another possibility is to use external USB or Thunderbolt hard-drives that users can take with them when they visit the satellite office. These portable disks need to be encrypted and have a proper backup strategy, obviously.


    ADSL is optimised for domestic use, basing a split-site business on it is going to end in tears. When designing your system look carefully at business continuity planning and the quality of service guarantee that comes with your ADSL. It will probably be delivered over some 40 year old piece of rat-chewed phone line and faults may take days or weeks to fix.

     

    C.

  • by gurdon,

    gurdon gurdon Apr 1, 2016 4:43 AM in response to gurdon
    Level 1 (4 points)
    Servers Enterprise
    Apr 1, 2016 4:43 AM in response to gurdon

    Dear Strontium90, John and Cdhw,

     

    Many thanks for the replies and good to know it is possible in theory. I feel I best clarify the setup a little in order to help understand the challenges.

     

    Site A

    Total users: 40-50


    Equipment:

    - Firewall on Dell Poweredge

    - 10 Macs Pros

    - X Server with 3TB storage (80% full)

    - Fibre line, 80Mbps down, 40Mbps up

     

    File Structure:

    - individual storage, limited to 1gb

    - shared storage per group of co-workers (3-7 users) - no limit

     

    File contents:

    - documents (10%)

    - large media files (0.5Gb - 5GB)

     

    We are looking to open at least one more location - Site B of a very similar setup - users would be expected to work from either location. The challenges we face is 1) - only ADSL connection is available at Site B and 2) - large media files.


    We do not expect live sync of large media files - these can take as long as needed and potentially can sync out of office hours entirely, but they should be available eventually. However, with 40 users Open Directory should be synchronised automatically in order to maintain user details up to date.


    Our plan was to establish a secure link via VPN and have a Replica Server at all additional locations, but the challenge was to establish local storage that syncs with Master OS X Server too.


    Is there a way to have a Replica Server with synced/cached storage?


    Many thanks for all replies - this is uncharted territory for me.


    Kind regards,

    Ian