Oracle database licensing rules make licensing on VMware cost prohibitive. Instead Oracle prefers that you use their "enterprise" virtualization product, Oracle VM. Avoid it at all costs. Threaten to migrate to MS SQL... just don't use this thing.
- Relatively inexpensive support
- Poor and buggy Windows client support. PVM network drivers have a serious performance bug that has not been resolved in more than a year (and three versions updates!). Luckily, there is a workaround where you can disable some features of the virtual NIC to get it working.
- "High Availability" in the OVM world means that if you shutdown a VM from within the OS, OVM automatically restarts it. If you want to actually shut down a VM you have to disable high availability, in which case you lose the ability to automatically migrate a VM if a host fails. It also means that you need to give your server admins access to the OVM Manager. For example, our DBAs can admin their Oracle servers... people who wouldn't normally have access to that level of enterprise management.
- It took three weeks and a set of consultants who knew little more than us to get storage and network working properly in a fault-tolerant manner.
- Non-existent best practices and no real community of support. Some Googling will find you the occasional blog or commercial site with tips and tricks, but they are few and far between.
- Poor management interface. In order to see the status of an individual VM you have to drill down to the correct host. There is no way to see the status of all VMs on all hosts.
- P2V is a multi-step process. Boot the server from a CD to turn it into a web server. Import web server into an OVM template. Create VM from template. Delete template. Essentially you need double the storage to get through the process.
- Minimal troubleshooting or diagnostic information without diving into the Linux OS.
- Training (virtual classroom only) was sub-standard and inconsistent. One member of our team was taught only to use the command line and was never shown the GUI. I was taught the GUI and some command line. And if you mention VMware in order to clarify concepts, prepare to get your head bitten off.
- Migrating VMs to different storage is an adaptation of the process for deploying from a template. Some inputs are ignored, and yet you are prompted for them anyway.
- You need an Oracle database to run the OVM Manager, which you install on the OVM Manager. So a key part of the infrastructure is a single point of failure.
- The SAN disk for the server pool is a single point of failure.
- If the OVM Manager goes down there is no way to manage the individual OVM hosts short of the Linux command line. The database (even when using Oracle Enterprise instead of the included Oracle XE) is prone to corruption, leaving you dead in the water. This has already happened to us once and the only solution from Oracle was to rebuild. Apparently this corruption is rather common. I know of other installations at my employer that have run into this corruption three times in the past nine months, requiring a rebuild each time. I do not feel that I can trust this product for a mission-critical production environment.
- Oracle is aware of these corruption issues but does not know the source and has no fix. They have reduced the incidence of corruption in version 3.2.3, but it is not a question of if corruption will occur, but when. The difficult thing is that the OVM manager will appear to run fine with this corruption.... until you restart the OVM manager, at which point it fails.
- The whole networking / storage / repository / configuration setup is needlessly complicated. I know this is an Oracle flavor of XEN, but... Citrix based their virtualization product on XEN and it isn't nearly as painful. Maybe Oracle should buy Citrix so they can drop OVM.
- Configuring storage that does not support their management plugins (entry-level EMC products) is an exercise in trial and error.
- If you already have another VM environment (VMware, Hyper-V) you are essentially setting up a parallel VM environment to manage.
- Cloning a VM (or cloning from a template) duplicates *everything* so be sure you don't have any ISO images attached, as they will be duplicated as well, chewing up storage.
- When you clone a VM the new files use the same name as the old with a number after it. If you don't think to rename them you will end up with a lot of files named "Windows 2008 Template (1)" "Windows 2008 Template (2)" and so on. The properties of the file will tell you to which VM it is linked, but (trust me) renaming them will save you a LOT of confusion. Things like this VMware just handles for you under the covers.
In summary: Do not use Oracle VM. If you must run Xen there are much better and manageable implementations (Citrix XenServer). If any reviewer has given Oracle VM more than two stars I seriously question whether they really have hands-on experience with the product (or have experience with a real virtualization product as a basis of comparison).
Update: After talking with other enterprises we are dropping OVM and setting up a separate VMware cluster in order to meet Oracle licensing requirements. While we will incur the expense of VMware licenses it is well worth it.
The licensing argument you will hear from Oracle regarding VMware is a scare tactic. You CAN run Oracle on VMware without breaking the bank on Oracle licensing if you plan carefully. VMware also guarantees that they will work directly with Oracle on your behalf to resolve any issues that may be linked to running on VMware.
Further update: When we gave up on Oracle VM about 9 months ago the central office tried to stick with it due to the Oracle DB licensing issues. Last week they got fed up and ordered the hardware to create a new VMware cluster dedicated to Oracle instead.
Another update: While I have not used Oracle VM since I posted this review, it is interesting to note that they have not released a new version since 2014. The latest version 3.3, did not fix any of the issues I don't think they are really serious about advancing or enhancing this product.
Which version of this solution are you currently using?