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Windows Server 2008 R2 Thread, Considerations for rebuilding a DC? in Technical; Originally Posted by rodent43 Question...do you run your file services as hardware servers? They're a mix of VM and hardware ...
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    Quote Originally Posted by rodent43 View Post

    Question...do you run your file services as hardware servers?
    They're a mix of VM and hardware based on location - we're running DFS-R in 14 different offices worldwide, so there's quite a mix.

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    Quote Originally Posted by Domino View Post
    They're a mix of VM and hardware based on location - we're running DFS-R in 14 different offices worldwide, so there's quite a mix.
    Thanks...the way we have file services set is via iSCSI as we could not afford fibre...we have two SANS, one used to store the VM images and one used for File Storage basically...so if we was to virtual the File Services we would then need to connect via iSCSI to the other SAN for storage...I am assuming this is possible with MS Hyper-V?

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    Quote Originally Posted by Ric_ View Post
    80/20 is a standard thing... go 50/50 if you want. Either way, you don't 'lose' any clients, you just lose the ability to give out new IPs... the clients don't throw the IPs away just because the DHCP server isn't there - of course, I'm assuming you haven't used a lease time of a nanosecond. If, in your environment, DHCP is such a vital service requiring high availability you can always move it onto your virtualisation setup.
    This is true, provided that the server is brought back online before the lease expires. If the leases expire before the server comes back presumably the machines will indeed throw their IPs away and seek a new one? Or will they realise they can't get a response and just hold on to the IP?

    Just put the fileserver role on your virtualised setup?
    We can look at this although at the moment we think trying to route iSCSI data from two different, logically and physically separated, SANS through a two virtual hosts and then into a virtual server could prove a headache.


    The services you were clustering before were different services... your issues all come from putting your DCs on clustered nodes and your replication has broken.
    I can't agree or disagree with this, I see no actual reason that clustering file services and the DHCP disk would break DC replication other than Microsoft says so?...

    What effects can the clustering possible have on the DC functions of the servers?! For all intensive purposes they are separate entities, their only link is in the fact that if C1 goes down while holding DHCP and, let's say the file service "Staff Share" then C2 will detect the failure and load it's instance of Staff Share and the DHCP disk, in the process keeping the DHCP leases and status and allowing reconnects back to Staff Share, including the ability (it would seem anyway) to resume existing file operations such as copies/deletes etc...

    I don't see how that simple migration can affect the DC functions at all, I understand the fact that if the server is overwhelmed it can fail to respond to the quorum sensing which can then trigger a failover but our servers are not that heavily loaded, if that became an issue in the future then naturally we can look at it.

    As I said before, this isn't any form of "I am better than you" it's just that I don't understand why people follow the status quo as I just don't understand the potential pitfalls. I am more than happy to redesign the backend if I can understand why I am doing it.

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    Quote Originally Posted by shadowx View Post
    As I said before, this isn't any form of "I am better than you" it's just that I don't understand why people follow the status quo as I just don't understand the potential pitfalls. I am more than happy to redesign the backend if I can understand why I am doing it.
    Lies....he thinks he is better than everyone

    watch he will correct my English now

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    Quote Originally Posted by rodent43 View Post
    Lies....(Generally 3 dots are used "etc...") He thinks he is better than everyone

    Watch, he will correct my English now
    Bloody cheek!
    Last edited by shadowx; 26th July 2012 at 11:49 AM.

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    Quote Originally Posted by shadowx View Post
    Bloody cheek!
    Good thing is...I have a lot of junk on my desk and he is within throwing distance

    Thanks for the comments...we will need to look in to moving the DCs...flat file systems, like Linux, are much easier, DHCP and DNS was mounted when used buy the node server and the eDirectory was replicated across most of the servers...thanks for all the posts, I am learning to think more MS by the day

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    Quote Originally Posted by rodent43 View Post
    Thanks...the way we have file services set is via iSCSI as we could not afford fibre...we have two SANS, one used to store the VM images and one used for File Storage basically...so if we was to virtual the File Services we would then need to connect via iSCSI to the other SAN for storage...I am assuming this is possible with MS Hyper-V?
    Yes that is possible. You can use the iSCSI initiator to connect to LUNs on different SANs, assuming they are on the correct network/VLAN and the hosts can see them. This would need to be a fresh LUN though as you'd need to format it for the CSV process to work.

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    rodent43 (26th July 2012)

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    Quote Originally Posted by Beard View Post
    Yes that is possible. You can use the iSCSI initiator to connect to LUNs on different SANs, assuming they are on the correct network/VLAN and the hosts can see them. This would need to be a fresh LUN though as you'd need to format it for the CSV process to work.
    Thanks beard...I was just reading about if the Virtual Host or Virtual Server should have the iSCSI Initiator Software, although it is slightly slower to put it on the virtual server, it will work...

    I will look at the SAN, as you said we would need to remake or use fresh LUNs which will cause a massive headache for existing data

    once again thanks for the response

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    Well there is no space left on the SAN to create new LUNs but I was just thinking, CSV would be for clustered storage...If we was to create a virtual file server for file services why would it be using clustered shared volumes?

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    Quote Originally Posted by rodent43 View Post
    Well there is no space left on the SAN to create new LUNs but I was just thinking, CSV would be for clustered storage...If we was to create a virtual file server for file services why would it be using clustered shared volumes?
    Sorry, misread the setup you have. If you aren't using CSVs then you can just use the iSCSI initiator to point at the current LUN. Even Easier!

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    Here is our theory...point out my obvious mistakes please...

    1. Create two new servers and add to existing cluster for File Services and DHCP
    2. Create a temp DC3 for luck
    3. Remove clustering from DC1 (remove DC from cluster) and demote
    4. Rebuild DC1 as new server and promote
    5. DC1 FSMO
    6. Demote DC2
    7. Rebuild DC2 and promote

    If the theory is right we will end up with 3 DC server, one of which will be temp DC3.
    We will have two servers running as file servers/dhcp in cluster

    All sound good in my head...probably not though

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    Quote Originally Posted by shadowx View Post
    This is true, provided that the server is brought back online before the lease expires. If the leases expire before the server comes back presumably the machines will indeed throw their IPs away and seek a new one? Or will they realise they can't get a response and just hold on to the IP?
    They hold onto it until next reboot usually.

    I can't agree or disagree with this, I see no actual reason that clustering file services and the DHCP disk would break DC replication other than Microsoft says so?...

    What effects can the clustering possible have on the DC functions of the servers?! For all intensive purposes they are separate entities, their only link is in the fact that if C1 goes down while holding DHCP and, let's say the file service "Staff Share" then C2 will detect the failure and load it's instance of Staff Share and the DHCP disk, in the process keeping the DHCP leases and status and allowing reconnects back to Staff Share, including the ability (it would seem anyway) to resume existing file operations such as copies/deletes etc...

    I don't see how that simple migration can affect the DC functions at all, I understand the fact that if the server is overwhelmed it can fail to respond to the quorum sensing which can then trigger a failover but our servers are not that heavily loaded, if that became an issue in the future then naturally we can look at it.
    Domain controllers 'chat' to each other replicating changes. This goes on all the time and there are mechanisms in place to ensure that old changes don't override new ones. If one of your DCs fails, the existing one(s) will continue operating and the changes still occur. Once the failed machine re-appears it catches up. This is all done so that you have the high availability of the AD services.

    By introducing the clustering, you introduce the ability for the changes not to replicate properly because of the way that clustering handles networking... adding and removing nodes as things fail and re-appear. This then confuses the updates and your DCs get out of sync. This is probably what has happened to you. Some roles (e.g. Hyper-V) are cluster aware and, in fact, depend upon the clustering service to provide high availability. Active Directory is not one of these roles.

    As I said before, this isn't any form of "I am better than you" it's just that I don't understand why people follow the status quo as I just don't understand the potential pitfalls. I am more than happy to redesign the backend if I can understand why I am doing it.
    The set up is not the status quo... the reason that everyone does it this way is because this is the way to set things up. Would you buy a piece of flat pack furniture and then assemble it the opposite way to how the manufacturer tells you to?

    Anyway, if you are in doubt of whether my recommendation works, our 40 DCs globally in 17 sites seem pretty happy.

    Quote Originally Posted by rodent43 View Post
    Here is our theory...point out my obvious mistakes please...

    1. Create two new servers and add to existing cluster for File Services and DHCP
    2. Create a temp DC3 for luck
    3. Remove clustering from DC1 (remove DC from cluster) and demote
    4. Rebuild DC1 as new server and promote
    5. DC1 FSMO
    6. Demote DC2
    7. Rebuild DC2 and promote

    If the theory is right we will end up with 3 DC server, one of which will be temp DC3.
    We will have two servers running as file servers/dhcp in cluster

    All sound good in my head...probably not though
    Just build a VM for file services and connect to the LUN on your SAN to pick up the files. Then follow what I said above - you need to follow what I said to make sure AD is fixed... the files will still be sat there on your SAN but you need AD replication to work.
    Last edited by Ric_; 26th July 2012 at 01:12 PM.

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    Quote Originally Posted by Ric_ View Post
    They hold onto it until next reboot usually.



    Domain controllers 'chat' to each other replicating changes. This goes on all the time and there are mechanisms in place to ensure that old changes don't override new ones. If one of your DCs fails, the existing one(s) will continue operating and the changes still occur. Once the failed machine re-appears it catches up. This is all done so that you have the high availability of the AD services.

    By introducing the clustering, you introduce the ability for the changes not to replicate properly because of the way that clustering handles networking... adding and removing nodes as things fail and re-appear. This then confuses the updates and your DCs get out of sync. This is probably what has happened to you. Some roles (e.g. Hyper-V) are cluster aware and, in fact, depend upon the clustering service to provide high availability. Active Directory is not one of these roles.




    The set up is not the status quo... the reason that everyone does it this way is because this is the way to set things up. Would you buy a piece of flat pack furniture and then assemble it the opposite way to how the manufacturer tells you to?

    Anyway, if you are in doubt of whether my recommendation works, our 40 DCs globally in 17 sites seem pretty happy.
    That's what I needed to know! Now it (almost) makes sense, it's still bad design from microsoft but now I understand why clustering isn't a great option so thanks for that. The thing is, Microsoft don't always make the best software so it makes sense they don't always provide the best instructions either...

    I have no doubt whatsoever of your indelible competence but one solution does not always fit all and so far in my experience a tailored solution is ALWAYS better than a generic solution that follows one set of instructions.
    Last edited by shadowx; 26th July 2012 at 01:19 PM.

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    Quote Originally Posted by Ric_ View Post
    Just build a VM for file services and connect to the LUN on your SAN to pick up the files. Then follow what I said above - you need to follow what I said to make sure AD is fixed... the files will still be sat there on your SAN but you need AD replication to work.
    The SAN and files are currently set up for a clustered solution...would one virtual server be able to use them LUNs or would we need to re-create them...

    If we create one virtual file services server we would not be able to cover software failure or is best to not worry about that for file services?

    thanks

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    Quote Originally Posted by rodent43 View Post
    The SAN and files are currently set up for a clustered solution...would one virtual server be able to use them LUNs or would we need to re-create them...

    If we create one virtual file services server we would not be able to cover software failure or is best to not worry about that for file services?
    Assuming that this is a 'normal' set up, the LUN used by the cluster is just the same as any other LUN, except 2 hosts can connect. The fileserver role is cluster aware so that works out which node should be writing and when.

    If you virtualise your file server, it will move between your hosts in case of hardware/software failure there. In the less likely event of software failure on the fileserver, just recover it from a snapshot or VM backup and re-join to the domain (the server will hold no data as it will use the software initiator to connect back to the data on a SAN).

    The main point of failure is your disk array... using the VM method, you could lose a host and a storage controller in each SAN and it will all still work. If you lose your disks in either SAN, you are screwed.

  19. Thanks to Ric_ from:

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