This chapter is from the book
This chapter is from the book
This chapter is from the book
Maintenance
Maintaining a vSphere-based virtual infrastructure is very important. After all, you have a large number of operating systems now running collectively on a much lesser amount of physical hardware in most cases. A failure to update for and then be exposed to a potential flaw may now put your entire infrastructure at risk instead of only some servers.
Why do organizations not properly maintain their vSphere environments? Everyone agrees with the criticality of maintaining servers whether it is through patches or regular release updates, but still it remains a large problem in many environments. In large part, the main driving force to perform any update is a result of an enhancement release that has added additional features.
Update Manager
One reason many administrators do not update their infrastructures is due to a lack of understanding of the process. Maybe they are new to VMware and never bothered to even install Update Manager with vCenter. Update Manager is not a requirement to patch systems but the process does become much more involved when using the command-line interface to do so. An administrator must download the update bundle and transfer it to each of the hosts. Then a command-line process must be invoked from each of the hosts. In the days before Update Manager, it is no wonder why some administrators might have chosen to patch less frequently or not at all.
vSphere is a hardened hypervisor and, as a result, needs much less patching and updating for vulnerabilities than a typical operating system. Many administrators, though, take this as a reason not to patch at all.
Some also entirely understand the advantages of Update Manager and have it installed and running. They realize how the effect of an issue with their vSphere infrastructures could now affect all their operating systems instead of just a handful. As a result, they view this increased impact of any updates as possibly negative. This may be the proper viewpoint as certain vulnerabilities may not be a high risk for their environments. They are further justified in their decision in knowing that the impact of any issues that occur in a virtual infrastructure can be huge if not properly planned. Perhaps the feature that is affected is also not something they are using. Being cautious and properly planning and testing for updates is certainly the way to go. To date, I have never worked directly with anyone who has been exploited by a VMware vulnerability. This is a true testament to the ability to harden the hypervisor and keep ahead of the curve with security exploits.
Again, that does not justify not patching. With the ever-increasing deployments of vSphere, it seems pretty reasonable to think the focus will continue to shift toward attacking these consolidated infrastructures powered by VMware. After all, wouldn’t it be easier to bring down 10 vSphere hosts running 200 servers than to try to bring them down individually?
Update Manager is a patch-management solution provided by VMware with all versions of vCenter Server. It helps to automate the deployment of patches and updates and provides a means to maintain compliancy among your entire infrastructure. Its capabilities are not just limited to vSphere ESXi hosts either, as you can now patch many virtual appliances as well as extensions such as the Cisco Nexus 1000V and EMC PowerPath.
Formerly, Update Manager was capable of remediating Windows guest virtual machines by providing operating system and application patches. As of vSphere 5, however, this capability is no longer included. Interestingly, they licensed the technology from Shavlik, which they recently acquired. VMware now offers several other products that offer comparable capabilities. vCenter Protect Essentials and VMware Go both offer abilities to patch and manage guest operating systems. vCenter Protect Essentials provides for an on-premise solution that will patch and manage virtual machines. In the case of VMware Go, it is a cloud-based solution that also offers capabilities for help desk end-user portals. Both products also provide asset and configuration management capabilities that are geared toward the small to medium business market.
A major selling point of utilizing Update Manager to patch your vSphere servers is that when set up and used properly, it requires zero downtime to any of your virtual machines. There is no need to worry about having to have downtime twice for virtual machines for both the vSphere and guest patching. Utilizing DRS in conjunction with Maintenance mode, an administrator can deploy patches to a host with zero downtime to any of the virtual machines in the entire infrastructure.
Update Manager also allows the scheduling of updates. Simply create or attach a baseline to a set of hosts and choose a date and time to run the updates. These baselines can be assigned at the vCenter level or at the datacenter, cluster, or host level. Another useful ability of Update Manager is to stage and schedule virtual machine hardware and tools upgrades.
Patching Hosts Using Update Manager
With a DRS-enabled cluster and the use of Maintenance mode, patching hosts using Update Manager is a straightforward process; however, the following key areas are often overlooked:
- Sizing the patch repository—The patch repository can become quite large depending on the versions of vSphere you choose to implement over time. As a result, it is best practice to configure a shared repository outside of the vCenter server or server where Update Manager is installed when separated. VMware offers the vSphere Update Manager Sizing Estimator for download, which will aid in sizing not only the shared repository, but also the database itself.
- Notification of new patches—You will have a hard time knowing when to install updates if you do not know when they come out. The easiest way to be notified of new patches is by configuring email notifications under the Download Schedule of Update Manager.
- Failure to consider compatibility and support—There is a lot to consider when choosing to install updates. If you are running a solution where the vendor will only support virtual machines on a certain revision of the software, then you should clarify how these support policies are affected by updates. This is a rarity these days as solutions such as Cisco’s unified communications on top of UCS software are fully supported by all updates at the time of release.
- Failure to disable HA during an update—If you have a smaller cluster of hosts, you might run into a failure if you do not disable HA during a host update. By default, this is not set but can be if you are going to run into this issue. Without doing so, if your cluster cannot support HA and you attempt a remediation, it will fail.
- Failure to properly configure DNS—If DNS is not properly configured, you will spend a lot of time troubleshooting why Update Manager is not working. It is highly dependent on DNS to be configured properly on both the vCenter and vSphere hosts. Failing to do so causes Update Manager to fail during the remediation.
Upgrading Hosts
VMware periodically releases new versions of vSphere that require an upgrade to vSphere. If an environment is healthy and no issues exist, we recommend using Upgrade Manager to upgrade the hosts in place. If, however, there are issues with your environment, consider wiping away each host and starting fresh.
You should also consider downtime in your environment for the upgrade. If your virtual machines are on shared storage backed by hosts that can vMotion among one another, you will be able to have much less downtime than an environment with virtual machines on local storage, for example. Different circumstances warrant different paths, so let’s talk about some of the key items to consider when planning your upgrade.
Planning for vSphere Upgrades
Planning for vSphere upgrades requires investigating your environment from top to bottom to ensure you are presently free of any issues and have the appropriate pieces to perform a successful upgrade of your environment. In fact, before an upgrade is the perfect time for a health check to be performed by a VMware authorized partner. Although this section describes the important steps to consider, you might also want to take a look at the vSphere Upgrade Guide provided by VMware.
Upgrade Entitlement
Before you get too far along, you need to ensure you are eligible to upgrade. Upgrades are not at an additional cost when you have a valid support contract with VMware for your purchased licenses. If you have an eligible support contract, you can find both the software and licenses available in your VMware software and licensing portals. If you don’t have an eligible support contract, you need to either renew your support or purchase additional licenses. In addition to support for vSphere, this is also a good time to ensure your hardware is still supported by your vendor before proceeding with an upgrade.
Feature Changes
Another consideration is changes that might have occurred between the old and new versions of vSphere. An example of this is an organization using Update Manager as part of vSphere 4 to patch its Windows guest. This functionality is no longer included as of vSphere 5; however, it can be acquired as part of vCenter Protect Essentials or Essentials Plus.
Hardware Compatibility
If your hardware is older, there is a chance that the hosts, storage, or IO devices might not be supported with the new release. Regardless of how new your equipment is, you should reference the VMware Compatibility Guide online to ensure the hardware will be supported after an upgrade. Although some people might not be concerned with hardware being fully supported, they should be advised that if it is not supported, there is a chance it will not work in some fashion. Be sure to check compatibility for your specific host. You will find that there may be several versions and revisions for popular brand models. Additionally, be sure to check your I/O devices and storage as well.
Database Compatibility
You need to be sure your database is supported with the new version of vCenter to which you will be upgrading. Many versions of SQL 2000 and 2005 are no longer supported despite their use, and you should consider upgrading the database servers if yours are not supported. Check out the VMware Product Interoperability Matrix online to verify your database software support before proceeding with any vCenter upgrades.
vCenter Support
You also need to ensure your vCenter server will support any older versions for hosts that are going to run for any period of time on an older version as part of that vCenter server. You can again check the VMware Product Interoperability Matrix online to verify this information. Pay close attention to the matrix, as shown in Figure 3.4. At the time of this writing, there is a known issue with VMware 4.0 U2 that does not allow it to be managed by a VMware vCenter server. This is a good example where a lot of people continue to make assumptions of the support to find out later that it does not work correctly.
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Figure 3.4 vCenter Compatibility and Support Matrix
Additionally, you need to make sure vCenter is installed on a 64-bit operating system. If your existing vCenter server is older, you might not be able to directly upgrade anyway; however, if it is installed on a 32-bit operating system, you definitely need to install a fresh operating system.
In addition to support, you must also see if an upgrade is possible. As shown in Figure 3.5, you can see that, in general, there is direct upgrade available from 4.0 U1 up to vCenter 5.0 with the exception of 4.0 U4. Both 4.0 and 4.0 U4, and even 2.4 U6, however, can be upgraded to 4.1 U2. Once at 4.1 U2, they can be updated to vCenter 5.0 directly. Always check the VMware Product Interoperability Matrixes and vSphere Upgrade Guide for the most up-to-date support information. Again, remember there is a 64-bit requirement, so if you don’t have a 64-bit server, you need to install a new version of Windows to support your new vCenter Server installation.
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Figure 3.5 vCenter Upgrade Compatibility and Support Matrix
Dependencies
Outside of the core functionality in the vCenter server and the vSphere hosts, there exist some other pieces that need consideration as well. These are just some examples and you need to also consider any additional software or plug-ins that are used in your environment. Make sure to consider these pieces by verifying support by the vendor or within the vSphere Upgrade Guide:
- vCenter Update Manager
- vCenter License Server
- VMware View
- VMware Data Recovery
- Site Recovery Manager
- Third-party plug-ins like PowerPath
- Use of Nexus 1000V
- Any PowerShell or other scripting used for troubleshooting and reporting
Upgrade Paths
vSphere 5 is the first version of vSphere that has been released in only the ESXi flavor, so there is only one destination when upgrading to vSphere 5. You must also consider the source of the server and whether you have the option to upgrade.
The following is true about upgrading older versions of ESX and ESXi to vSphere 5.0. Note there are conditions where these items might not apply, so be sure to check the VMware Product Interoperability Matrixes and vSphere Upgrade Guide for the most up-to-date support information.
ESX & ESXi 3.5
- No direct upgrade available
- Upgrade to 4.x first
- Note that the partition layout might be incompatible with vSphere 5, so this can prohibit such an upgrade to 5.0
ESX & ESXi 4.0
- Direct upgrade available with Update Manager, interactively, or scripted
- Might not be compatible with all environments
- For example, ESX 4 hosts on SAN/SSD might not have optimal partitions and disks with multiple VMFS partitions cannot be upgraded
- Additionally, note that a host with any third-party vSphere Installation Bundles (VIB) may require using the ESXi Image Builder CLI to create a customized ESXi install ISO
And one last note on upgrading hosts. As of vSphere 5, the advanced version no longer exists and any customers with active support agreements for vSphere 4 Advanced are entitled to vSphere Enterprise.
Order of Operations
When laying out your plan for an upgrade, you must consider the order in which you are going to do so. Outside of the vCenter and vSphere hosts themselves, you need to make sure you upgrade to supported code and firmware for your storage and other devices ahead of time. Additionally, be sure you have proper backups of the necessary components. For vCenter, you need at minimum a backup copy of the database as well as Secure Socket Layer (SSL) certificates from the server. For the hosts themselves, you need to have good documentation on their configuration as well as a backup copy of all virtual machines. This holds especially true if you are upgrading a host with virtual machines running on local storage. For virtual machines on shared storage, you need to ensure backups exist as you will be upgrading our virtual hardware and VMware Tools later on.
In general, follow these steps to perform an upgrade:
- Run the vCenter Host Agent Pre-Upgrade Checker. This can be found on the vCenter installation media and is a great verification tool to ensure the likelihood of a successful upgrade.
- Upgrade or install a new vCenter server.
- Upgrade or install a new Update Manager.
- Upgrade or install other plug-ins and third-party packages.
- Upgrade or install vSphere on hosts.
- Upgrade VMFS.
- Upgrade virtual machine tools and hardware.
Methods for Upgrading vSphere
As discussed previously, to perform your vCenter upgrade, you can either upgrade the software in place if supported or install a fresh vCenter server. You can then choose to either start completely fresh, redefine roles and other vCenter configurations, or import the database and continue from there.
For vSphere hosts, you not only have the option of upgrading or starting fresh, but you also have several methods to perform the upgrade. When possible, we recommend building new hosts and bringing configurations over.
In previous versions of vSphere, the Host Update Utility was included on the vCenter installation media for performing host upgrades on a host-by-host basis. Note that this is no longer the case and you must upgrade your hosts by either using vSphere 5 media or through Update Manager.
Manual Upgrade
You may manually perform an upgrade to a host using the ESXi installation media by performing an interactive or scripted upgrade. It is recommended you disconnect all storage from the host as this greatly reduces the amount of time required for the upgrade.
When upgrading a host, you have three options:
- Upgrade ESXi, Preserve VMFS Datastore or Force Migrate ESXi, Preserve VMFS Datastore
- Install ESXi, Preserve VMFS Datastore
- Install ESXi, Overwrite VMFS Datastore
The first option will vary if any custom VIBs are not included with the vSphere 5 media. If that is the case, Force Migrate ESXi replaces Upgrade ESXi. Make sure to back up any items on the local VMFS datastore beforehand and especially when choosing to overwrite the VMFS datastore.
In addition to performing an interactive upgrade, you may also choose to perform a scripted installation. For full details on creating a scripted installation, including adding custom drivers and third-party VIBs, check out the vSphere Upgrade Guide.
Update Manager
When using Update Manager to upgrade hosts, an orchestrated host upgrade can occur that allows not only for vSphere host installation, but the installation of VMware Tools and the upgrade of virtual hardware.
Update Manager does have some limitations that you may encounter. Recall from the earlier discussion of upgrade paths that there are some limitations even when following a supported path. Update Manager cannot be used to upgrade an ESX 4.x host if it was previously upgraded from 3.x as a result of insufficient space in the /boot partition. This problem is not unique as it is possible an ESX 4.x host may also not have the proper amount of space.
If you are not installing a fresh version of vSphere, it is recommended to use Update Manager because it greatly eases the upgrade process. The use of Update Manager does a better job of preventing erroneous actions and disallows things such as upgrading the virtual machine hardware before installing VMware Tools.
Host Upgrades Upgrading a host requires the creation of a host upgrade baseline. Additionally, you are required to import the ESXi image to be used for upgrades.
You may choose to have separate baselines and separate images in the repository. For example, you may have different images based on hardware for the hosts, which may be of different vendor types and contain different third-party VIBs.
You cannot roll back to the previous version of ESX/ESXi when upgrading with Update Manager, so, as always, make sure you have the configuration of your host documented and the proper backups of all virtual machines in place before proceeding with any upgrades.
Virtual Machine Upgrades Upgrading virtual machines after an upgrade requires using an existing baseline or the creation of a baseline group. You cannot upgrade VM hardware until the virtual machine is running the latest version of VMware Tools. Update Manager makes sure this happens to avoid these operations not occurring in sequence.
By default, the following two baselines are created:
- VMware Tools Upgrade to Match Host
- VM Hardware Upgrade to Match Host
When scheduling the update, you can granularly schedule separate virtual machines depending on the following power states. For example, you might want to schedule any powered-on machine later because they will require downtime, as shown in Figure 3.6. Your options for scheduling virtual machine updates include the following:
- Powered On
- Powered Off
- Suspended
An orchestrated upgrade of virtual machines is not required but greatly reduces the time it takes to remediate a large number of virtual machines at the same time. If you would rather manually remediate the virtual machines, simply upgrade VMware Tools on each virtual machine and then power off the virtual machine to perform the virtual hardware upgrade.
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Figure 3.6 Scheduling Update Manager Updates