System DBs and Instances all on one LUN

[umbletech]

Hi All

I've been tasked with creating an SQL cluster which a number of systems will use for database services. What they've given me to work with is a bit different to how I'd lay it out.

What I've been given is two TB LUNs on a mid-level FC SAN. So the SQL binaries will go on local disk and the system databases and a number of databases in named instances will be all sharing one big LUN/(drive in windows).

Am I likely to run into implementation or performance issues with this setup?

 

[mrdenny]

You'll probably run into issues with performance as you start putting more load onto that one LUN. What sort of disks are behind it, and what else is on those LUNs?

I'd work on getting those LUNs rebuild in a more useful config.

Denny
MVP
MCSA (2003) / MCDBA (SQL 2000)
MCTS (SQL 2005 / SQL 2008 Implementation and Maintenance / Microsoft Windows SharePoint Services 3.0: Configuration / Microsoft Office SharePoint Server 2007: Configuration)
MCITP Database Admin (SQL 2005/2008) / Database Dev (SQL 2005)

My Blog

 

[umbletech]

Thanks for your reply.

The LUNs are dedicated Database tier so won't be sharing with other uses but it's a consolidated service so there will be a lot of different databases with different load profiles.

I assume we can have multiple named instances per node as long as we have multiple resource groups.

But actually is this going to work at all? Won't each instance be dependent on a disk resource and so have to be different disk.

 

[JayKusch]

Seems to me that you need to re-carve your one big LUN into a couple if not a few physical LUNS.

If you have on big LUN you are going to soon or later start seeing issue with read/write issues.

I would look at creating a LUN for TLogs, a LUN for Data and maybe a LUN for TempDB/backups at the very least.

Best practices dictates splitting your TLogs and Data files on seperate physical discs at a bare minimum.

Hope this gets you started on the right path.

Thanks

J. Kusch

 

[umbletech]

Thanks all.

So basically I'll have to re-carve. And as per my previous SAN experience you have to design for I/O throughput first then for capacity.