Posts tagged EVA

SCVMM 2012 – Deep Storage Integration

Many new cool functionalities were added to SCVMM 2012. In this blog I focus on the very deep Storage integration which can be accessed from the Fabric wunderbar.

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One of the new features in SCVMM 2012 is integration with SAN storage arrays. The primary reason for this is of course there is not much point in building a Hyper-V Private Cloud without some sort of Fibre Channel, iSCSI or Shared SAS based type of shared storage.

Very much focusing on the standards that are available, Microsoft decided to employ the SMI-S Provider for this purpose, with VDS as a temporary option for backwards compatibility. Apart from managing software I had not had the pleasure to work with SMI-S before and I guess it is new for most of my readers. So let me first delve into what SMI-S really is.

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Come See the MMS 2011 Private Cloud

The MMS 2011 Hands-on-Labs are based on HP’s Reference Configuration for Hyper-V Private Cloud. Here is the story in pictures. There are 400 labs and the 1600 virtual machines required for those labs are provisioned in 10 minutes, six times a day. System Center is used to manage the private cloud which is based on Hyper-V Server 2008 R2 SP1, HP EVA storage and HP c-Class BladeSystem 2-socket G7 servers with FlexFabric.

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HP MPIO Full Featured DSM for HP EVA now supports Cluster Shared Volumes

In an HP Storage Works EVA Best Practices document published in February 2010, we were advised not to use the HP MPIO DSM with Cluster Shared Volumes, but as an alternative to use Microsoft Native MPIO only. This was unfortunate because the HP MPIO Full Featured DSM allows for better visibility and control of the multiple paths between Hyper-V R2 host and its storage.

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During a storage change in one of our datacenters, we noticed that not all nodes were able to see all CSV disks. The Hyper-V R2 cluster we were working on has eight cluster nodes. On another occasion, one of my cluster MVP colleagues, Edwin van Mierlo, had explained to me that in a Hyper-V R2 cluster with CSV, the number of SCSI registrations can add up very quickly.

In our case we work with an 8-node Hyper-V R2 cluster with HP BL490c blades and HP EVA6400 storage array with 20 LUNs.

Each CSV LUN counts as one SCSI Reservation. The coordinator node makes a persistent reservation for each LUN it owns in the cluster. Because all other nodes in the cluster must be able to read/write to that same LUN (CSV with Direct I/O), they must register all possible paths to that LUN, dependent on one of the following two registration methods:

  1. Storage that require a registration per path
  2. Storage that require a registration per Initiator

The software on the host will send a registration over all of the paths. So the Storage will receive a registration REGISTER_ IGNORE_EXISTING_KEY on all paths. It is then up to the storage to do the correct thing.
http://www.freepatentsonline.com/EP1246060.html

In a two node cluster this would mean:

Example: 2 node cluster, 2 Initiators per node, 4 paths per Initiator, 1 Disk (CSV) :

For Storage "class" A, per path registration, you get:

  • 16 registrations (4 paths x 2 initiators x 2 nodes x 1 disk)
  • 1 reservation (from 1 node in the cluster that owns the disk)

For Storage "class" B, per Initiator registration, you get:

  • 4 registrations (2 nodes x 2 initiators)
  • 1 reservation (from 1 node in the cluster that owns the disk)

In an 8-node cluster with 20 CSV disks, the number of registrations go up quite significantly:

For Storage "class" A, per path registration, you get:

  • 1280 registrations (4 paths x 2 initiators x 8 nodes & 20 disks)
  • 20 reservations (from all nodes owning an online disk)

For Storage "class" B, per Initiator registration, you get:

  • 16 registrations (8 nodes with 2 initiators)
  • 20 reservations (from all nodes owning an online disk)

I am not sure what method HP uses for HP EVA, but I hope it is “class” B. If anyone knows, please let me know!

While searching for other cases with CSV problems in HP EVA environments I struck on this important piece of news:image

The author of the blog refers to a newly released version of HP MPIO Full Featured DSM v4.01 which fully supports Cluster Shared Volumes with Windows Server 2008 R2

See the original blog: http://blogs.technet.com/b/hugofe/archive/2010/06/18/hp-dsm-support-with-csv.aspx

  • Download the software here.

  • Download the release notes here.

  • Important parts:

    if there is a stray reservation on a disk device, the device becomes inaccessible to the host systems connected to it. This is because the strong reservation type (persistent reservations) supports load balancing in clusters. You can use the persistent reservations clear utility that comes with HP MPIO EVA DSM package to remove the stray reservations.”

    Note: For Microsoft Windows Server 2008 and Windows Server 2008 R2 Failover cluster to work properly, set the array host mode on the HP CommandView EVA to ‘Microsoft Windows LH’ or set custom host mode to “00000004198009A8”.

    In the CommandView we use (v9.2.1) we don’t have the Microsoft Windows LH host mode option.

    If you issue the hpprutil devices command you can see this:

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    You can clear the reservation with hpprutil clear devices

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    We finally seem to have some light at the end of the tunnel about Hyper-V R2 clusters and mysteriously disappearing cluster shared volumes.

    Hyper-V R2 hotfixes for DPM 2010

    Install at least these two hotfixes on Hyper-V R2 servers:

    • KB975354 A Hyper-V rollup package dealing with parallel backups on same cluster shared volumes and VM’s hosted by different servers; Avoiding data truncation as a result of simultaneous backup of VM from host and from within virtual machine; properly restoring a VM with snapshots to another location
    • KB975921 You may be unable to perform certain disk-related operations after an exception when a hardware provider tries to create a snapshot in Windows Server 2008 R2 or Win 7.

    Although not specifically related to Hyper-V and DPM2010, I also install hotfix KB974909 which solves loss of the network connection within a virtual machine with heavy outgoing network traffic and many concurrent network connections. This could easily be the case when a VM level backup is being conducted.

    There is also a list of tested hardware VSS providers:
    http://blogs.technet.com/dpm/archive/2010/02/05/tested-hardware-vss-provider-table.aspx

    I may have a chance to test the HP LeftHand VSS hardware provider, which is not yet on this list. The HP EVA 4×00, 6×00 and 8×00 is on the list by the way.

    A comprehensive list of Windows updates and hotfixes for Hyper-V and Hyper-V R2 can be found here:
    http://technet.microsoft.com/en-us/library/dd430893(WS.10).aspx

    If you need to update your Hyper-V servers, you might just as well include this recent security update:

    Microsoft Security Bulletin MS10-010 – Important
    Vulnerability in Windows Server 2008 Hyper-V Could Allow Denial of Service (977894)
    http://www.microsoft.com/technet/security/bulletin/ms10-010.mspx

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    When you try to protect VM’s on a Hyper-V R2 clusters with DPM2010 RC you now get a warning if the required hotfixes are not installed.

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    This is very helpful!