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Multiple Clusters in Private Cloud RRS feed

  • Question

  • Dear All.....What would be desirable/recommended in a Private Cloud setup.....To have a single cluster with N number of nodes with N number of CSV.....OR Multiple Clusters with limited number of nodes as well as CSV....Thanks.
    Tuesday, September 3, 2013 4:51 AM

Answers

  • What do you feel comfortable with?  What are your criteria for recovery times?

    I don't think you are going to find any hard and fast rules on this.  The reason Hyper-V can now support up to 64 nodes in a cluster is because customers were asking for it.  So some customers want large clusters.  I have seen other customers who feel more comfortable managing only 4-8 nodes in a cluster.

    Changes in 2012 R2 enhance the management of large clusters.  The ability to dynamically modify quorum according to the number of nodes in the cluster makes management of large clusters more flexible.  The CSV load-balancing is another feature to make the management of a large cluster easier.  So, Windows Clustering keeps improving for those customers that are willing and capable of managing and troubleshooting a large cluster, but some people still feel comfortable with a smaller environment.

    Some might say that there are fewer 'wasted' resources in a larger cluster.  Though this may be truer when comparing a 2-node cluster, in which you have to ensure you have enough resources on a single node to run the desired workload should one node go down, to an 8-node cluster, in which a lost node's workload can spread across seven others, there are other considerations in a larger cluster.  In most larger clusters that I have seen, it is common to have two or three 'spare' nodes and one or two nodes for management of things like backups.

    Again, I don't think there are any hard and fast rules.  Maybe if you laid out some of the issues you are looking to address others with experience in those areas could chime in.  A broad, open-ended question like yours does not provide much of a target for people to reply to.


    .:|:.:|:. tim

    Tuesday, September 3, 2013 1:33 PM

All replies

  • What do you feel comfortable with?  What are your criteria for recovery times?

    I don't think you are going to find any hard and fast rules on this.  The reason Hyper-V can now support up to 64 nodes in a cluster is because customers were asking for it.  So some customers want large clusters.  I have seen other customers who feel more comfortable managing only 4-8 nodes in a cluster.

    Changes in 2012 R2 enhance the management of large clusters.  The ability to dynamically modify quorum according to the number of nodes in the cluster makes management of large clusters more flexible.  The CSV load-balancing is another feature to make the management of a large cluster easier.  So, Windows Clustering keeps improving for those customers that are willing and capable of managing and troubleshooting a large cluster, but some people still feel comfortable with a smaller environment.

    Some might say that there are fewer 'wasted' resources in a larger cluster.  Though this may be truer when comparing a 2-node cluster, in which you have to ensure you have enough resources on a single node to run the desired workload should one node go down, to an 8-node cluster, in which a lost node's workload can spread across seven others, there are other considerations in a larger cluster.  In most larger clusters that I have seen, it is common to have two or three 'spare' nodes and one or two nodes for management of things like backups.

    Again, I don't think there are any hard and fast rules.  Maybe if you laid out some of the issues you are looking to address others with experience in those areas could chime in.  A broad, open-ended question like yours does not provide much of a target for people to reply to.


    .:|:.:|:. tim

    Tuesday, September 3, 2013 1:33 PM
  • Dear All.....What would be desirable/recommended in a Private Cloud setup.....To have a single cluster with N number of nodes with N number of CSV.....OR Multiple Clusters with limited number of nodes as well as CSV....Thanks.
    There's no black or white there are just shades of gray. So N-node cluster sharing a single CSV is BAD. You'll kill all I/O on distributed lock manager passing access token every time to the different cluster node. Many clusters are hell to manage. So break your N into a set of N/M "cluster groups" (you cannot migrate a VM easily away from your cluster without VM downtime) and provide an every cluster node with a dedicated CSV to keep redirected mode access as low as possible. With a smart management and a virtual SAN you'll manage to keep nearly all of th I/O local (except writes need to be confirmed on the partner(s) node(s)) so performance would be comparable to running VMs from DAS and having no cluster (and cluster management overhead) at all. That's the way cloud providers do (Well... They're mostly using Xen and DRBD but idea is the same).

    StarWind iSCSI SAN & NAS

    • Proposed as answer by VR38DETTMVP Tuesday, September 3, 2013 7:42 PM
    Tuesday, September 3, 2013 7:42 PM
  • Apart from the user workload VMs discussed about, you could consider putting your Private Cloud management VMs (e.g. System Center products) on their own 2-node cluster. Separation at this level is considered best practice - it may also help your upgrade path giving you the option of upgrading your management infrastructure and s/w independently of your user application workload.

    Wednesday, September 4, 2013 2:06 AM