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HA works the way it should and all VMs die.

Sunday, October 16th, 2011

Was working at a customer site doing some VMware and Microsoft work. Came in around 1pm and couldn’t get to anything. We couldn’t ping any VM’s. I could however ping the ESXi hosts. I used the vSphere client to connect to each host individually and saw that all VMs were turned off. At the time I had no clue why they were off. The only thing I saw on one of the hosts was that we had lost network redundancy on one of the hosts.

I asked one of the guys if they did anything on the hosts and they said no. I talked to another guy and he had someone else reboot the switch. A little background, all of the ESXi hosts are connected to the same switch (bad) and didn’t separate NICs. When the switch was unplugged all of the hosts determined that they were in Host isolation mode and the way HA was set up was that they were supposed to shut down the VMs.

The purpose of this is so that if one host does get isolated then the VMs will shut down and get restarted on a different host. However since all hosts believed they were isolated they all shut down their respective VMs and sat there doing nothing with all VMs shut off. What would have prevented this would have been to have 2 switches and one NIC connected to each switch. I didn’t design this network, and know it is not best practice to do this, but it was interesting to see this happen. We were doing maintenance on the weekend, so it was no big deal, but imagine the repurcussions is you only have one switch and it fails during the day and all VMs go down. Not good.

VMware on NetApp NFS

Thursday, February 24th, 2011

This information was taken from a NetApp white paper by Bikash Roy Choudhury – TR-3839. I am just pulling out snippets that I thought were very interesting. Not all of it is specific to NetApp, but most of my consulting work is on NetApp.

  1. Deduplication - A VMware datastore has a high level of data duplication. This is because it contains many instances of the same guest operating systems, application software, and so on. NetApp deduplication technology can eliminate this duplicated data, dramatically reducing the amount of storage required by your VMware environment. Space savings range from 50% to 90%, with 70% being typical.
  2. Strongly consider using CAT6 cables rather than CAT5/5e. GbE will work on Cat5 cable and retransmissions will recover from any errors that occur, but they have a more significant impact on IP storage networks.
  3. NFS NETWORKS AND STORAGE PERFORMANCE - There are three primary measures of storage performance: bandwidth (MBps), throughput in I/O operations per second (IOPS), and latency (ms). Throughput and bandwidth are related in the sense that the throughput measured in Mbps equals to IOPs multiplied by the I/O size. The I/O size is the size of the I/O operation from the host perspective.IOPS are usually determined by the back-end storage configuration. If the workload is cached, then it‘s determined by the cache response; most often, it‘s determined by the spindle configuration for the storage object. In the case of NFS datastores, the storage object is the file system. On a NetApp storage system, the IOPS achieved are primarily determined by the number of disk drives in an aggregate.

    You should also know that each NFS datastore mounted by ESX (including vSphere) uses just one TCP session to an NFS datastore carrying both NFS control information and NFS data. Because of this, the upper limit throughput achievable from a single ESX host for a single datastore—regardless of link aggregation—is a single link. If you use 1GbE, this means that a reasonable expectation is a unidirectional workload of ~80–100MB/sec (GbE is full duplex, so this can be 160MB/sec bidirectionally with a mixed workload). Higher total throughput on an ESX server can be achieved by leveraging multiple datastores. You can scale up the total throughput to multiple datastores using link aggregation and routing mechanisms.

    The performance described above is sufficient for many use cases. Based on these numbers, NFS is appropriate for various VMware scenarios:

    • A shared datastore supporting many VMs with an aggregate throughput requirement within the guidelines above (a large number of IOPS, but generally not large-block I/O)
    • A single busy VM as long as its I/O load can be served by a single GbE link

    With small-block I/O (8K), a GbE connection delivers 12,500 IOPS—roughly the performance of 70 15K spindles. On the other hand, a SharePoint VM tends to use I/O sizes of 256K or larger. Using 256K I/O sizes yields just 390 IOPS, which would likely be a problem. Under such circumstances, 10GbE may be the best performance option. If you use 10GbE—though a single TCP session will be used per datastore—much more throughput is available for demanding workloads. If 10GbE isn‘t an option, you can use NFS for some VMs over 1GbE and FC or iSCSI for others depending on the application throughput and latency requirements.

  4. Partition Alignment - For NFS, there is no VMFS layer involved, so only the alignment of the guest VM file system within the VMDK to the NetApp storage array is required.The correct alignment for a new VM can be set using either diskpart to format a partition with the correct offset or by using fdisk from the ESX service console. In practice to avoid further creating of improperly aligned VMs, you must create templates that are properly aligned so new virtual machines built using those templates are properly aligned. NetApp has created a tool: mbralign, to check and correct the alignment of existing virtual machines.
  5. THIN PROVISIONING - As mentioned above, the ability to take best advantage of thin provisioning is a major benefit of using NetApp NFS. VMware thin provisions the VMDK files on NFS datastores by default, but there are two types of thin-provisioned virtual disk files available:
    • “Thick” type thin-provisioned virtual disk.This type of virtual disk file is created by default on NFS datastores during the virtual machine creation process. It has the following properties:
      • Creates a flat .VMDK file; does not occupy actual disk blocks (thin provisioned) until there is a physical write from the guest OS
      • Guaranteed disk space reservation
      • Cannot oversubscribe the disk space on the NFS datastore
    • “Thin” type thin-provisioned virtual disk.You must create this type of virtual disk file using the vmkfstools command. It‘s properties are:
      • Creates a flat .VMDK file; does not occupy actual disk blocks (thin provisioned) until there is a physical write from the guest OS
      • No guaranteed disk space reservation
      • Can oversubscribe the disk space on the NFS datastore

    You can run the following command against an NFS datastore to show its actual disk space utilization:

    • # vdf -h /vmfs/volumes/<NFS Datastore Name>

    Using the “thin” type of virtual disk you have the option to oversubscribe the storage capacity of a datastore, allocating more space than a datastore actually contains on the assumption that VMs will not all use the capacity allocated to them. This can be a very attractive option; however, it has a few limitations that you must know about before you implement it.

    Should an oversubscribed datastore encounter an out-of-space condition, all of the running VMs will become unavailable. The VMs simply “pause” waiting for space, but applications running inside of VMs may fail if the out-of-space condition isn’t addressed in a short period of time. For example, Oracle databases will remain active for 180 seconds; after that time has elapsed the database will fail.

  6. High Availability and Disaster Recovery - NetApp recommends the following ESX failover timeout settings for NFS. We recommend increasing the default values to avoid VMs being disconnected during a failover event. NetApp VSC can configure these settings automatically. The settings that NetApp recommends (across all ESX hosts) are:
    • NFS.HeartbeatFrequency (NFS.HeartbeatDelta in vSphere) = 12
    • NFS.HeartbeatTimeout = 5(default)
    • NFS.HeartbeatMaxFailures = 10. When the number of NFS datastores are increased, we also recommend increasing the heap values: Net.TcpipHeapSize =>’30′ to Net.TcpipHeapMax => ‘120′
      1. Back up your Windows registry.
      2. Select Start>Run, type regedit.exe, and click OK.
      3. In the left‐panel hierarchy view, double-click HKEY_LOCAL_MACHINE, then System, then CurrentControlSet, then Services, and then Disk.
      4. Select the TimeOutValue and set the data value to 190 (decimal).

    Every “HeartbeatFrequency” (or 12 seconds) the ESX server checks to see that the NFS datastore is reachable. Those heartbeats expire after “HeartbeatTimeout”(or 5 seconds), after which another heartbeat is sent. If “HeartbeatMaxFailures”(or 10 heartbeats) fail in a row, the datastore is marked as unavailable and the VMs crash.

    This means that the NFS datastore can be unavailable for a maximum of 125 seconds before being marked unavailable, which covers the large majority of NetApp failover events.

    During this time period, a guest sees a non-responsive SCSI disk on the vSCSI adapter. The disk timeout is how long the guest OS will wait when the disk is non-responsive. Use the following procedure to set operating system timeouts for Windows servers to match the 190-second maximum set for the datastore:

    1. Back up your Windows registry.
    2. Select Start>Run, type regedit.exe, and click OK.
    3. In the left‐panel hierarchy view, double-click HKEY_LOCAL_MACHINE, then System, then CurrentControlSet, then Services, and then Disk.
    4. Select the TimeOutValue and set the data value to 190 (decimal).

4 Reasons Virtualization Saves Money

Wednesday, December 1st, 2010

By Heather Clancy

Most articles about virtualization discuss the technology in the context of “big” business. They are glowing about the potential for “data center consolidation” or “reduced system maintenance expenses.” Or they rave about the prospects for a better disaster recovery plan, better security and extra flexibility for employees.

What about small business? The good news is if you are a small business owner, there are plenty of short- and long-term benefits from virtualization-and you don’t need a big budget. (That makes virtualization attractive in a brutal economic climate.)

So what is virtualization? Quite simply, it is technology that explodes the traditional one-to-one relationship between computer hardware and the software that runs it. Virtualization software allows you to create two or more complete computing environments on a single piece of hardware. The proliferation of systems with multi-core microprocessors has made virtualization possible across a wide range of business applications.

Here’s a big benefit: Instead of buying more than one server for your growing small business, you can “virtualize.” In fact, many things can be virtualized beyond servers: desktop systems, storage devices and even networks. Virtual memory, for example, allows a computer to “borrow” from disk storage to extend its available memory resources-enhancing the user experience without you even realizing it. Likewise, one physical server, which runs one application, can be transformed to look like multiple servers when virtualization technology is applied.

“The key message is really focused on cost savings,” says M.J. Shoer, president and virtual chief technology officer for Jenaly Technology Group, Portsmouth, N.H., which provides IT services for small and mid-size businesses. “In terms of managing the server, it doesn’t really change anything. At the same time, we have found that it opens up new opportunities for new applications and processes.”

The benefits of server virtualization for small businesses are many. The good news: If you use Microsoft software as your technology infrastructure, you will reap the benefits, since server virtualization is a core consideration and principle of the Microsoft Windows Server 2008 platform through the Hyper-V product.

Without getting too esoteric, there are four tangible benefits your company can realize by investing in a virtualization strategy.

1. Add another business application or database without increasing the number of physical hardware servers you have to worry about.

No matter how good you are at financial planning, it’s tough to anticipate when your company may need to accommodate an influx of new employees or new customer accounts that could put a strain on your technology resources.

Shoer cites the example of a client, an 18-person business, that was already running two servers and that was evaluating a new, dedicated system to run a customer relationship management (CRM) application. Shoer’s team determined that by investing in slightly more robust multiprocessor hardware, the customer could replace one of its existing servers with a virtualized machine that ran both the new application along with the old ones. What’s more, the investment laid the groundwork for its team to work remotely, while still retaining access to the applications they needed to do their jobs. The server hardware that Shoer’s customer bought in order to make this happen was on the high side of what it would have had to pay for a dedicated server (between $5,000 and $10,000), but it now only needs to be concerned with the ongoing maintenance costs for one piece of hardware that acts like two servers. So, the company still has only two physical servers to manage, but it has extended the productivity of its employees while adding another application.

2. Cut back on energy consumption and technology maintenance costs.

Microsoft customer HotSchedules in Austin, Texas, which offers online scheduling services for the restaurant and hospitality industry, and serves as one of Microsoft’s case studies for virtualization, was able to accommodate rapid growth by migrating to Windows Server 2008 with the Hyper-V virtualization technology.

Because HotSchedules provides online services as its core product offering, each time it adds a certain number of new customers, it needs to invest in the technology backbone to support their accounts seamlessly, even in times of peak usage. Before it moved to a virtual architecture, the company reported that it would sometimes take weeks to provision a new server. With Hyper-V, that process has been cut down to a day or less. What’s more, the case study reports that by running up to 19 virtual machines on each of its physical servers HotSchedules was able to reduce power costs by up to 77% compared with the energy it would have needed to run a comparable number of “real” systems.

Energy costs and maintenance concerns were two big considerations for Linda Chan, senior information technology director of Veeco, a midsize manufacturing company in Plainview, N.Y., who was asked to organize a corporate facility consolidation that combined two nearby facilities.

Chan says virtualization made sense for her organization because her company was able to save space, cut its energy consumption and respond to requests for new applications or increased processor power in a matter of hours. Her company realized the return on its investment in new servers and the virtualization software within 18 months.

She advises those considering virtualization: Invest in a server assessment to determine whether virtualization is right for your company. That’s because some server applications, such as ones that rely on specialized peripherals or add-on cards like fax servers or engineering applications, cannot be used in a virtual environment. Veeco’s assessment provided valuable financial information Chan needed to prove the case for virtualization to her CEO.

“We were able to achieve getting greener,” she says. “I can now bring up a server in a couple of hours, or less than that. I’ve had times when a server is underpowered, and I’ve turned on another processor. These are things I couldn’t do if we hadn’t virtualized.”

3. Enhance your disaster recovery plan.

One very real strategy made possible by virtualization is a disaster recovery plan. Guy Baroan, founder and CEO of Baroan Technologies, an information technology solution provider in Elmwood Park, N.J., says virtualization allows a small business to create ongoing back-up snapshots image of a database or business application that can be replicated in more than one place.

If the main piece of hardware fails, the application can be restored from the fail-over server in a matter of two hours versus 72 hours. Most small businesses are horrified by the thought of their systems being out of commission for more than a day, so this message really resonates, Baroan says.

The rise of quad-core server hardware has made this process simpler and more affordable. “This might cost a small business a little more in terms of RAM or storage, but they can do so much more with that one server and the virtualization software,” Baroan says.

4. Stretch your technology budget.

Jay Tipton, CEO of Technology Specialists, a company in Fort Wayne, Ind., that provides technology services to small businesses, called on virtualization to help a 15-employee company that needed to run multiple e-commerce sites for its business. The licensing for the software application used to run the stores required them to be managed separately.

Tipton says this business may have been forced to buy and set up three different hardware servers. But it was able to buy a single system to run all three stores-running separately using virtualization software. This same company added another virtual server that allows employees to access certain databases remotely, Tipton says.

Koji Mori, director of network services for Calsoft Systems, a technology services company in Torrance, Calif., says pressure is building for small businesses to realize incremental value out of their spending, and technology is often the first place they should look.

Virtualization is compelling because it enables short-term and long-term cost reductions in systems maintenance, office real estate and electrical footprint. The additional upfront expense comes in the form of the virtualization software, which he says is minimal if you use a Microsoft platform; a hardware upgrade or refresh; and some additional implementation services. At a minimum, this will be 20% less than the cost of buying a second server, Mori says.

Companies with as few as two servers can realize an immediate benefit from virtualization, he says. “The situation is very rare where someone cannot handle a virtual environment,” he says. “We’ve migrated things as old as Windows NT 4 applications onto virtualized platforms.”

Heather Clancy is an award-winning business journalist and high-tech communications strategist who has covered technology for more than 20 years. She writes frequently about small-business technology issues and contributes to the GreenTech Pastures blog about technology and the environment on ZDNet. She can be reached via e-mail at heather@heatherclancy.com.

VMWorld 2008

Friday, September 19th, 2008

Probably the biggest surprise of VMWorld 2008 is that they did not announce ESX 4, although the guy running my PowerShell scripting seminar said that certain features in the beta of the VI Toolkit (their platform for using PowerShell) take advantage of ESX 4, like the ability to hot-add RAM to a VM.

 

One of the most significant products announced here VDC-OS, is summed up in this article.  http://virtualizationreview.com/news/article.aspx?editorialsid=10197 , also discussed on VMware’s site here: http://vmware.com/technology/virtual-datacenter-os/ .  In a nutshell, it allows management of ALL VirtualCenter Servers from one screen, it introduces a new version of the VIC an allows for things like searching for all VMs that have been running for a month.  In the results pane of the search, you can make changes to all in that group.  In other words, if the search returned 4 VMs, you could then install/upgrade the VMware Tools on all 4 VMs right there.

 

Another that they talked about is renaming VirtualCenter Server to vCenter.  The product will have a linked mode, so that when you use VDC-OS, and you make a change to say, a role named Night Manager on one VC, it will go into the centralized backend and then automatically populate to all VCs!  I asked if it was granular, it is not.  It’s an all or nothing feature, you can’t say, send to all VCs, except VC28.

 

With this technology, licenses will also be centralized and will have the ability to have security put on them.

 

Another product they mentioned was vCenter Administrator Portal (VCAP), which is a web-based Appliance that connects to and works across  multiple VC’s.  It allows for some functions across VCs, hosts and VMs, like the VDC-OS, but there is no linked mode because it will work with VC 2.0 and 2.5.  It should be out in 30 days.  It provides a search based interface.  As a demo, he asked it to display all powered on VMs.  It allows you to launch a VIC to manage hosts as well.

 

Also, they said, “Customers need tools to maintain and configure ESX hosts consistently across the datacenter.”  Their answer is called Host Profiles. These profiles are the following:

o   Host Profile = Collection of root sets (Like a Role = collection of Privileges)

o   You make the configuration you want for ESX Hosts on a single “golden” ESX host (used to create a host profile - export)

o   Attach it to host or cluster & apply profile to host or cluster

o   Any new ESX hosts added, get profile automatically.

o   Can check hosts for compliance

o   Can bring hosts into compliance

 

Finally, they announced that ALL events in VC will be “alarm-able”.  I think that feature is a subtle but significant step forward for better monitoring and security.

 

More to come later.  By the end of September, all the sessions, slides, and lab files will be available on the VMWorld site for attendees to download.  I will do a more comprehensive review on those once I get them.  JSW

When Large Data Centers Roamed The Earth

Friday, July 11th, 2008

Chicago, IL

Almost a year ago my phone rang, and on the other end of the receiver was a familiar voice. An old friend of sorts. I was a busy COO working on all the pressing issues of our marketing, sales, consulting and web businesses at the time, and the idea of taking on another project seemed impractical. So you can imagine my surprise when I was given the directive to stop the presses and make a 90 degree turn in direction and start working on coming up with a training solution in the virtualization market. I was like, “Virtualization?” “ VM What?” “What is that?”

For almost 2000 years the primary mode of transportation in the world was the horse and buggy. Then came along a guy named Henry Ford and the model T automobile, and since then, in the last 100 years we have gone from that to putting a man on the moon!

When you stop to think about it, it is pretty incredible. Globally, more has been accomplished in the last century than the prior 2000 years put together. Now, with the advent of computers and the information age, the life of a job, let alone an industry has decreased drastically. What used to take 40 years for change now takes less than three. And from all appearances it is only going to move faster as virtualization is revolutionizing the world we live in.

Virtualization is emancipating the IT infrastructure world from the constraints of needing physical servers to run data centers. Soon, IT professionals will reminisce of the days when large data centers were housed in buildings instead of closets, draining financial resources to heat and cool rooms to maintain a constant temperature. Where a phone call in the middle of the night meant disaster and recovery, and lost sleep. Oh the good ole days. Soon young IT professionals will be like my children today, asking their parents what it was like back then when there were no TV’s? How did you live without cell phones and the internet? Like the dinosaurs in today’s history museums, they will have to imagine what life was like back when virtualization didn’t exist.

There is no denying it. Virtualization is changing the way we do things and is probably one of the hottest technological break-throughs that have happened in the IT field since the proliferation of high speed Internet connectivity to the masses. And as people like me, and company’s begin to look seriously at virtualization the benefits are simply amazing. I keep pinching myself to make sure I am not dreaming. Beyond the obvious benefits virtualization presents in the form of cost savings and an environmentally friendly solution, perhaps the most subtle benefit to the infrastructure professional is now they are no longer the anchor in a company’s ability to grow, but rather the force multiplier that can help an enterprise, big or small, gain a competitive advantage through dynamic scaling of IT resources. What used to take days or weeks, now can be accomplished in minutes.

While the possibilities virtualization presents in its many applications are exciting, there is still a lot to know, and very few places to go and receive training and certification on the subject. Research shows that a virtualization certification commands one of the highest wages today in the IT market place. However, having a certification does not necessarily mean you know what you are doing as many training solutions are incomplete, or hybrids that pull from various sources. As we found as we began our homework, we soon learned not all training is the same, and there was allot of room for improvement when it came to training in virtualization, hence the phone I received a year ago.

So the decision was made to become the premier provider of training on the topic of virtualization, and to become an advocate for those companies who are driving the virtualization revolution. Be it VMware, Microsoft’s Hyper-V, or any of the other 98 or so virtualization related technologies out there, our goal is to help the IT Professional transform themselves into a subject matter expert on the topic of virtualization through high quality, affordable training solutions. Because we are not a manufacturer of virtualization, we maintain our independence and objectivity as we are not peddling any particular product, and have no preset agenda. Our sole mission is to advance the cause, and support you the student on the journey. We hope you join our community, take advantage of our training offerings, become certified and earn higher wages. One thing is for sure, If you are in IT, you don’t want to miss the Virtualization Training window of opportunity.

See you on the other side!

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