Tag: Storage

KB2838669–A Big Hotfix Bundle For WS2012 Failover Clustering

The Failover Clustering group also released a big update today.  It solves a range of issues.

Issue 1
Consider the following scnario:

  • You have the Hyper-V server role installed on a Windows Server 2012-based file server.
  • You have lots of virtual machines on a Server Message Block (SMB) share.
  • Virtual hard disks are attached to an iSCSI controller.

In this scenario, you cannot access to the iSCSI controller.

Issue 2
Consider the following scenario:

  • You have a two-node failover cluster that is running Windows Server 2012.
  • The cluster is partitioned.
  • There is a Cluster Shared Volume (CSV) on a cluster node, and a quorum resource on the other cluster node.

In this scenario, the cluster becomes unavailable.

Note This issue can be temporarily resolved by restarting the cluster.

Issue 3
Assume that you set up an SMB connection between two Windows Server 2012-based computers. The hardware on the computers do not support Offloaded Data Transfer (ODX). In this situation, the SMB session is closed unexpectedly.

Issue 4
Consider the following scenario:

  • You have a Windows Server 2012-based failover cluster.
  • You have a virtual machine on a CSV volume on the cluster.
  • You try to create a snapshot for the virtual machine. However, the snapshot creation is detected as stuck. Therefore, the snapshot set is aborted.
  • During the abortion process of the snapshot, the CSV volume is deleted after the snapshot shares are deleted.

In this scenario, the abortion process is paused automatically because of an error that occurs on the cluster.

Issue 5
Assume that you have a Windows Server 2012-based failover cluster. Two specific snapshot state change requests are sent from disk control manager to CSV proxy file system (CSVFS). The requests are present in the same message. In this situation, disk control manager is out-of-sync with CSVFS.

Issue 6
Assume that you create a snapshot for a CSV volume on a Windows Server 2012-based failover cluster. When the snapshot creation is still in progress, another snapshot creation is requested on the same CSV volume. In this situation, the snapshot creation fails and all later snapshot creation attempts on the CSV volume fail.

Note You cannot create a snapshot for the CSV volume until the volume fails over or the volume goes offline and then back online.

Additionally, the update also resolves the issues that are described in the following Microsoft Knowledge Base (KB) articles:

  • KB2799728: Virtual machine enters a paused state or a CSV volume goes offline when you try to create a backup of the virtual machine on a Windows Server 2012-based failover cluster
  • KB2801054: VSS_E_SNAPSHOT_SET_IN_PROGRESS error when you try to back up a virtual machine in Windows Server 2012
  • KB2796995: Offloaded Data Transfers fail on a computer that is running Windows 8 or Windows Server 2012
  • KB2813630: Virtual machine enters a paused state or a CSV volume goes offline when you try to create a backup of the virtual machine on a Windows Server 2012-based failover cluster
  • KB2824600 Virtual machine enters a paused state or goes offline when you try to create a backup of the virtual machine on a CSV volume in Windows Server 2012.

A supported hotfix is available from Microsoft.

KB2836988 – May 2013 Update Rollup For WS2012 and Win8

It was a busy day for Microsoft releasing hotfixes today.  This includes another UR bundle of hotfixes.  There are a few in here that are relevant to Hyper-V, etc.  As usual, this update rollup is available via the Windows Catalog (WSUS, etc).

KB2836121 – An update for Storage Spaces in Windows 8 and Windows Server 2012 is available

This article describes an update for Storage Spaces in Windows 8 and Windows Server 2012. After you install the update, Storage Spaces will prioritize regeneration. Specifically, the regeneration time is shorter, but the available bandwidth for the regular I/O buffer is decreased.

2833586 – Virtual machine does not come online after you add a pass-through disk to the virtual machine in Windows Server 2012

Consider the following scenario:

  • You have a Windows Server 2012-based failover cluster. 
  • A Hyper-V server role is installed on the cluster node.
  • You create a virtual machine on the cluster node, and then you configure the virtual machine as a cluster resource.
  • You add a pass-through disk to the virtual machine by using Windows Management Instrumentation (WMI).

In this scenario, the virtual machine does not come online.
Note If you add the pass-through disk by using the Failover Cluster Management snap-in, the virtual machine does come online.

Another WS2012 Hyper-V Converged Fabric Design With Host & Guest iSCSI Networks

Back in January I posted a possible design for implementing iSCSI connectivity for a host and virtual machines using converged networks. 

In that design (above) a pair of virtual NICs would be used for iSCSI, either in the VM or the management OS of the host.  MPIO would “team” the NICs.  I was talking with fellow Hyper-V MVP Hans Vredevoort (@hvredevoort) about this scenario last week but he brought up something that I should have considered.

Look at iSCSI1 and iSCSI2 in the Management OS.  Both are virtual NICs, connecting to ports in the iSCSI virtual switch, just like any virtual NIC in a VM would.  They pass into the virtual switch, then into the NIC team.  As you should know by now, we’re going to be using a Hyper-V Port mode NIC team.  That means all traffic from each virtual NIC passes in and out through a single team member (physical NIC in the team).

Here’s the problem: The allocation of virtual NIC to physical NIC for traffic flow is done by round robin.  There is no way to say “Assign the virtual NIC iSCSI1 to physical NIC X”.  That means that iSCSI1 and iSCSI2 could end up being on the same physical NIC in the team.  That’s not a problem for network path failover, but it does not make the best use of available bandwidth.

Wouldn’t it be nice to guarantee that iSCSI NIC1 and iSCSI NIC2, both at host and VM layers, were communicating on different physical NICs?  Yes it would, and here’s how I would do it:

image

The benefits of this design over the previous one are:

  • You have total control over vNIC bindings.
  • You can make much better use of available bandwidth (QoS is still used)
  • You can (if required by the SAN vendor) guarantee that iSCSI1 and iSCSI2 are connecting to different physical switches

Don’t worry about the lack of a NIC team for failover of the iSCSI NICs at the physical layer.  We don’t need it; we’re implementing MPIO in the guest OS of the virtual machines and in the management OS of the host.

Confused?  Got questions?  You can learn about all this stuff by reading the networking chapter in Windows Server 2012 Hyper-V Installation And Configuration Guide:

9781118486498 cover.indd

Storage Spaces Inside a Virtual Machine Is Not Supported

I’m hooked on Storage Spaces, the mechanism in Windows Server 2012 where we can aggregate non-RAID disks and create thinly provisioned (optional), fault tolerant volumes, just like you’ve been doing on a modern SAN (but Storage Spaces is more flexible, if not as feature rich).

It appears that some like this feature so much that they’ve started to implement it inside of virtual machines:

THIS IS NOT A SUPPORTED CONFIGURATION

Sure, you might see presenters like myself do this in demos.  I make it clear: I only do this because I don’t have the hardware to do Storage Spaces at the physical layer.  Storage Spaces was designed to be created using physical disks … and then you can store your virtual machines on a Storage Space virtual disk.

Why are people implementing Storage Spaces in a production VM?  My primary guess is that they want to aggregate virtual hard disks to create a larger volume.  VHD format files can only expand up to 2040 GB.  OK … that’s the wrong way to go about it!  The correct solution would be one of the following:

  • Deploy Windows Server 2012 Hyper-V and use VHDX files.  They scale out to 64 TB – the maximum size of a VSS snapshot BTW.
  • If you’re stuck on vSphere (2 TB VMDK) or pre-WS2012 Hyper-V (2040 GB VHD) then (I hate saying this …) use a physical disk of some kind until you can upgrade to a scalable hypervisor like WS2012 Hyper-V and convert to the more flexible VHDX.

A second possible excuse is: “I want to create volumes inside a VM”.  Anyone who has spent any time owning a virtualised platform will laugh at this person.  There is a simple rule in our business: 1 volume = 1 virtual hard disk.  It gives us complete flexibility over volume management both at the physical (placement) and virtual (resizing) layer.  If you need an E: volume, hot-add a VHDX to the SCSI controller.  If you need an F: volume, hot-add a VHDX to the SCSI controller.  If you need to expand the G: volume, expand the G: VHDX and then expand the G: volume.

The other reason I expect to hear via comments is “we’re scared of virtual hard disk corruption so we want to RAID the disks in some way using Storage Spaces”.  Where to start?

  • I have never personally witnessed a corrupt virtual hard disk.  When I have heard of such things it’s because people do stupid things with snapshots or differential disks and they deserve what follows.
  • The VHDX format has built-in protection for corruption that can be caused by power loss.
  • DOING STORAGE SPACES INSIDE A VM IS NOT SUPPORTED!  It’s no one’s fault, other than yours, when it misbehaves or breaks.

Please, just start using VHDX format virtual hard disks ASAP.

Blogging On The Petri IT Knowledgebase

Update your RSS feeds: I have just signed up with the Petri IT Knowledgebase to write about Microsoft virtualisation.  I will absolutely be continuing to blog on here.  My goal is to do different kinds of topics on both sites.

Yes, I know this site has been kind of quite in the last 2 weeks – I’m snowed under with prepping and delivering presentations for various road shows and events.

You can see part 1 of my newest article on Petri, where I start exploring the various kinds of storage that you can use in a Hyper-V virtual machine.

Passthrough Disks –ARE– Still Supported By WS2012 Hyper-V Live Migration, But With Limits

I recently reported on a new KB article that says:

Changes and improvements in Windows Hyper-V Server 2012 no longer support pass-through disks if Live Migration is to be used.

In other words, Live Migration was allegedly not supporting the use of passthrough disks.

That article was incorrect. 

The story is:

1) Hans Vredevoort told me that found a contradicting blog comment/response by Jeff Woolsey where he stated that Live Migration of VMs with passthrough disks would be supported in what I’ll call legacy scenarios:

Pass through disks are still supported with Windows Server 2012 Hyper-V Live Migration (just like they were with Windows Server 2008 R2 Hyper-V) as long as the migration of a clustered VM and the pass through disk is managed by the cluster. For migrations outside of a cluster, such as:

  • Shared Nothing Live Migration or
  • Using standalone hosts with file on a SMB share (without clustering enabled)

…pass through disks aren’t supported because the pass through disk doesn’t have a way to move between hosts.

That makes total sense.  The passthrough disk (which is not a CSV) has to be passed from one host to another, and only a cluster-managed disk can do this.

Therefore the new scenarios in WS2012 Hyper-V cannot support Live Migration.  Again, that makes total sense:

  • Non-clustered SMB-stored-VM Live Migration – you can’t store a LUN on a file share!
  • Shared-Nothing Live Migration – until you can transport a LUN from one server to another Star-Trek-style, it isn’t happening.

2) Who was correct, Jeff Woolsey or the KB article?  We needed clarity so I reached out to the Hyper-V group in Redmond.  They responded overnight and Jeff was right.  The KB article was … a … bit enthusiastic (I personally loved the message – I’m quite clear in my training that I’ll smack anyone who I find using passthrough disks).  In fact, that KB article has been deleted by Microsoft.

So those of you who are panicking about your passthrough disks, you can calm down now.

…

However …

The advice from everyone who knows anything about Hyper-V is that you should switch to using VHDX files.  This isn’t just me.  Check out any of the Virtual Machine MVPs on this topic.  Read what Didier Van Hoye or Hans Vredevoort (both being the top 2 storage guys in our group IMO) have to say on the topic.

  • VHDX scales out to 64 TB
  • It has new health features to limit corruption
  • It supports 4K sector matching for performance
  • It offers the legacy VHD types, where Fixed will be nearly the same speed as the underlying disk

I heard loads of complaints over the “death” of passthrough disks in the last 7 days.  To you I say, you need to put down your toys of the 2000s. and join us in the 2010s.  We virtualise now for flexibility.  The business demands it, and passthrough disks are not flexible.

The one argument I’ll give some credence to is “I can’t hot expand a VHDX”.  If you are hot expanding LUNs every couple of days then you’ve got other issues, but I too would like this feature.

Anywho, panic over.  You can Live Migrate a VM with passthrough disks as long as both the VM and the passthrough disks are managed by a Hyper-V cluster.  I’m going back to my lazy vacation day now.

Event – Two Day Deep Dive On Windows Server 2012

Microsoft Ireland are running a free 2-day technical deep dive event on Windows Server 2012 on April 22-23 in Dublin.  The agenda is below.

Monday22nd April

9:00 – 9:30         

Registration
   

9:30 – 10:00       

6 month update (L 100)

10:00 – 11:00     

Fundamentals – storage & networking) (L 200)

11:00 – 11:15     

Coffee

11:15 – 13:00     

Storage – iSCSI, Storage Pools, DeDupe (L 300/400)

13:00 – 13:45     

Lunch

13:45 – 15:00     

Networking – DHCP, SMB 3.0 NIC Teams, DA (L 300/400)

15:00 – 15:15     

Coffee

15:15 – 16:60     

Active Directory, inc. DAC (L 300/400)

16:30                   

End

Tuesday23rd

9:30 – 11:00       

Hyper-V (L 300/400)

11:00 – 11:15     

Coffee

11:15 – 13:00     

Virtual Networks (L 300/400)

13:00 – 13:45     

Lunch

13:45 – 15:00     

Mini-MMS

15:00 – 15:15     

Coffee

15:15 – 16:30    

Mini-MMS

16:30                   

End

A large collection of Microsoft speakers appears to be presenting the content.  I’m presenting the 2 highlighted sessions on Hyper-V and storage.

Remember, there are also some regional events that will be discussing the reasons to upgrade to Windows Server 2012 that are starting next week.

Over 1 Year Since The Project Started

Well over a year ago discussions started with the publisher.  A lot of that was “will this version of Hyper-V actually sell?” which leads to “will there be enough demand for a book on this product?”.  6 months of writing by 4 authors and reviewing by another, plus countless hours of editing.  And after all that work, 600 pages just arrived.

You can get 600 pages of Windows Server 2012 knowledge to own from these outlets: Smile

Yes, I know there are some typos still there – please contact Wiley directly.

Frequently Asked Questions: FAQ.

KB2819564–Corruption Occurs When Merging Data Deduplication-Enabled VHDs In WS2012

Strictly a storage (or storage virtualisation) KB article, but relevant to Hyper-V admins, this post describes when data corruption occurs when you merge Data Deduplication-enabled VHDs in Windows Server 2012.

Symptoms

Assume that you enable Data Deduplication on a virtual hard disk (VHD) on a Windows Server 2012-based computer. The computer crashes while you are merging VHD files. In this situation, data corruption occurs in the VHD files.

To resolve this issue, install the Windows 8 and Windows Server 2012 cumulative update 2822241 (available via Windows Update).

KB2821052 – “0x000000D1” Stop Error When Opening MPIO Snap-In WS2012 Computer

This isn’t a Hyper-V bug, but it’s one that those using SAN storage should pay attention to … and that often include Hyper-V admins/engineers: "0x000000D1" Stop error when you open the MPIO snap-in on a computer that is running Windows Server 2012.

Symptoms

Consider the following scenario:

  • You connect a storage device that is controlled by Microsoft Multipath I/O (MPIO) to a computer that is running Windows Server 2012. 
  • You remove all paths to the storage device.
  • You open the MPIO snap-in or try to switch to the MPIO tab on the properties window of a disk that is managed by MPIO.

In this scenario, the computer crashes. Additionally, you receive a Stop error message that resembles the following:

STOP: 0x000000D1 (parameter1, parameter2, parameter3, parameter4)

Notes

  • This Stop error describes a DRIVER_IRQL_NOT_LESS_OR_EQUAL issue.
  • The parameters in this Stop error message vary, depending on the configuration of the computer.
  • Not all "Stop 0x000000D1" errors are caused by this issue.

A supported hotfix is available from Microsoft.

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