I'm currently a sysadmin who's been given a database consolidation project. I have a plethora of small databases (the vast majority are under 10GB, with a handful between 30 & 100GB). Most of the databases have small memory and cpu requirements, however a few are struggling with I/O at the moment.
Currently they're spread out across multiple servers with a mix of SQL 2000 to 2012. I need to consolidate these (into 2012) and am after some guidelines.
I'm thinking of grouping databases within the same instance, unless I have a security consideration or an issue with compatibility. Is it true that single instances generally offer better performance (eventhough multiple instances use multiple TempDB files)?
Setting the min and max memory on a single instance is straightforward, however I'm not too sure when using multiple instances. I was planning to take the overall guest memory, minus 4GB or 10% (whichever is the greater), then divide the remaining memory by the number of guests and use that as the max memory per instance. I'm planning on setting the min memory to a 1\4 of max.
I'm planning on running the SQL upgrade advisoron all DBs, then migrating (backup & restore) them to SQL 2012 compatibility mode 110. I'm also planning on setting the autogrow properties for the database, log and model DBs beforehand.
I've read that putting TempDB on a separate LUN improves performance. I assume this only applies if the LUN actually equates to separate physical disks (as opposed to a LUN on the same set of spindles as the logs or database)?
Is there much of an advantage to using filegroups for small databases? From my understanding filegroups can improve performance by separating out parts of a database onto muliple\faster disks (i.e. putting read\archive data on raid 5). I've also read that the downside to filegroups is the complexity and not much benefit unless your database is close to 1TB
As the current servers will be virtualised, I'm planning on using a 1:1 virtual to physical core mapping, starting with 1 core per server and will increase if needed.
Any advice\feedback would be appreciated.
Thanks
