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koln5
Starting Member
29 Posts |
 Posted - 2011-05-11 : 15:31:19
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| Hi folks..high overall question;If you take money out of the equation, what is "better" ?... a virtual SQL Server or real box SQL Server ?What are the top advantages and disadvantages for each case..remember, money is not one.Im asking, because my network people are pushing for virtual machines, and I feel that as a DBA, Im losing somewhat of control of my SQL farm. I was just wondering if I should be pushing back to keep my real box servers.Thank you for your reponses. |
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tkizer
Almighty SQL Goddess
38200 Posts |
Posted - 2011-05-11 : 15:33:29
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| A physical server is better for performance reasons. My environment consists of both. Although we have some production databases on VMs, most of our VMs are for test environments. Our systems are too critical, have too high of availability requirements, and too high of performance requirements to even consider using a VM. Remember that VMs share resources, no matter how much separation they do.Tara KizerMicrosoft MVP for Windows Server System - SQL Serverhttp://weblogs.sqlteam.com/tarad/Subscribe to my blog |
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russell
Pyro-ma-ni-yak
5072 Posts |
Posted - 2011-05-11 : 16:09:02
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| I'd have to say this really depends. I just built a ton of SQL Servers in a new data center, where they are all virtualized.All of my testing shows that the new VMs far outperform the standalone boxes in the old data center by a significant margin in every way you care to measure it.There are some caveates however:Yes, resources are shared, but I can throw an awful lot of CPU and RAM and I/O throughput at the new VMs. But the VM server could be a single point of failure (it isn't in my case, but could be in many other installations).You have to be very careful with thin provisioning and over-provisioning.You need to be careful which servers (depending on resource usage) are allowed to share the same host machines.In cases where CPU, RAM and I/O resources are equal, the answer to "which is better" is "it depends." Though 4 years ago I would have said that physical machines are clearly better.If you allow a single VM Host to be a single point of failure, you could be in for big trouble on mission critical applications. You can build failover clusters out of VM clients, but it doesn't protect you from the host going down.In our case, we won't deprecate the "physical" data center. We're using SAN replication (deltas only) to keep it in synch with the "Virtual" data center.We also have multiple VM servers and failover plans tested and in place.We used to have 2 physical DCs, now we've virtualized what was our secondary and are preparing to make it our primary. Primary DC will become the secondary. We also have a fast dedicated pipe between the two.Further, we have failover plans in both DCs so there are no single points of failure in either DC, and if one DC becomes unavailable altogether, the other will keep on rolling. In fact, during testing, we were able to disable either or, but they could still communicate with each other.That's a long winded answer, but the point is, that we have a high throughput mission critical system that for us, virtualization is better. It is far cheaper, and far easier to manage from a network standpoint (not any easier or harder from a DBA's viewpoint however). Setup isn't easy though, and neither was the planning and research. |
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Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)
7020 Posts |
Posted - 2011-05-11 : 16:21:58
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| A big advantage is that the virtual server is not tied to a particular piece of hardware, so as long there is enough host hardware capacity available, you can keep the server running even if one or more hosts are down.We have about 50 SQL Servers running on virtual machines, both dev and production. As long as you allocate enough resources for each machine, they should be OK.Another advantage of VMs is that you can do a physical to virtual migration to be able to quickly get SQL Servers off of old hardware without having to setup a new server. That’s also good for situations where there’s an application installed on the server, especially when there’s no one that know how to re-install it, the vendor no longer supports it, or you don't have the media.CODO ERGO SUM |
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russell
Pyro-ma-ni-yak
5072 Posts |
Posted - 2011-05-11 : 21:15:59
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| Regarding Michael's remarks...we just installed SQL, and mounted the SAN volumes for the actual lighting up of the VMs. Doesn't get much easier than that!No data migration from an I/O standpoint...!I will add a second warning about provisioning disk space though. We can extend volumes or add volumes at will without restarting Windows. But one needs to be very aware of over provisioning. |
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dinakar
Master Smack Fu Yak Hacker
2507 Posts |
Posted - 2011-05-11 : 23:51:52
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| which software you use for creating the virtual machines also plays an important role. Hyper-V VMs have different limits in terms of amount of CPU, processors, RAM that can be allocated and VMWare VMs have different limits. Also VMWare has different kind of supportability for certain scenarios such as they only support 2 node cluster (on VMs) etc. Like Russell mentioned, few years back it was almost a no brainer. However things are different now. The ease of provisioning, the high availability options such as Live Migration in Windows 2008 etc have changed the picture. It is definitely worth a discussion now.Dinakar Nethi************************Life is short. Enjoy it.************************http://weblogs.sqlteam.com/dinakar/ |
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dinakar
Master Smack Fu Yak Hacker
2507 Posts |
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Virtual SQL Server vs Real SQL Server