In a web application architecture with 1 app server (IIS) and 1 database server (MSSQL), if you had to pick one server to virtualize in a VM, which would it be: web or db?
Generally speaking of course.
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A:
I would probably decide depending on the amount of computation required by the app server, versus the amount of computation/io done by the database.
With that said I would think most of the time the DB should NOT be virtualized. Virtualization isn't too hot for db's that have to ensure that data remains nice and safe on a disk, and adding another abstraction layer can't help with that.
Snazzer
2009-04-22 05:08:16
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A:
If you have two physical servers there is no need to virtualise - use one server for IIS and one for the database.
If you have one physical server there is also no need to virtualise.
If I had to choose, it would be the web server. The database would benefit in terms of performance by running on a physical server. If the web server is virtualised, it makes it quick and easy to clone it to create a cluster of web servers.
Anthony
2009-04-22 05:08:54
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A:
With today's hypervisors and best practices you can virtualise both infrastructures. When you virtualise your DB infrastructure it is best to ensure that the DB is installed onto a SAN based system so that IO performance is not a bottleneck.
As with everything there are the right and wrong way of doing things but following vendor best practices and testing will enable you to squeeze the best performance out of your VM instances.
There are plenty of whitepapers and performance testing from the various vendors should you want to virtualise your entire infrastructure.
Even though virtualisation again is an industry hot topic with various vendors now giving away hypervisors for free, this does not mean that using virtualisation is the way forward. Server consolidation yes, performance enhancing maybe - YMMV
Wayne
2009-04-22 05:35:15
Whitepapers from vendors. Not users.
gbn
2009-04-22 05:38:37
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A:
Web of course.
Databases require too much IO bandwidth + It's easier to add instances or databases to a single instance, whereas isolated web servers benefit more.
Similar question... "Run Sharepoint 2003 on VMWare?". Sharepoint is just an asp.net application with a SQL Server back end.
gbn
2009-04-22 05:41:50
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A:
The shortcoming of most virtual environments is I/O, especially disk. SQL is very I/O intensive. I am using a shared virtual host and the slow I/O is killing me.
That said, Microsoft is pushing SQL on Hyper-V. It's a hypervisor, which means its a thinner layer between the VM and the hardware, and the drivers are quasi-native. Here's their whitepaper: http://download.microsoft.com/download/d/9/4/d948f981-926e-40fa-a026-5bfcf076d9b9/SQL2008inHyperV2008.docx
Looks like for SQL, you will lose ~10% performance overall. The upside is that you can move the whole instance to another box quickly, bump up the RAM, etc.
Another thing to consider is Intel's enterprise SSD drives (X25-E). I imagine that would help a lot in a virtual environment. Pricey, of course.
Matt Sherman
2009-04-22 06:41:44