RAID, SAN & Equality on DEVL & PROD environments

[rbowers]

Does anyone have information on storage set up? We are brand new to DW/BI on SQL Server 2008. We are a mainframe shop with source data in DB2 Z/OS. We have read many conflicting articles on storage and whether to use RAID 1 or RAID 5 on local or SAN. We also heard in class that you should try to set up EQUAL DEVL and PROD environments as much as possible. Currently, our storage admins want to set us up with PROD on SAN RAID 5 but our DEVL on local RAID 1. It seems to me we would experience significant differences in our performance testing but we are being asked to prove it will be a problem. Anyone have any helpful information? And, if it causes a problem, how difficult is it to change later?

[ngalemmo]

I would certainly insist on a consistant architecture across dev, QA and prod environments, while problably not identical capacities. The exeception would be sandbox environments, which, by their nature are unstable and experimental.

[Jeff Smith]

The Disk structure of Development doesn't need to the be the same as Production, but I prefer to have Test and production to be identical. It makes it easier to see the impact of tweaking indexes, queries, etc on the performance of reports.

We are using SQL Server 2005 with an EMC SAN. I'm told that SAN is a completely different animal. The more we learn about SAN, the more we are have to change our way of thinking. I asked the SAN administrator if creating a database using 1 logical drive vs several logical drives made a difference. He said, "No". In the past, we created file groups and tables in a way that the indexes were on 1 logical drive, fact tables on another logical drive and dimension tables on a another logical drive. I was told that there is no performance gain from such a set up. I'm being told that there is no reason to have more than 1 file group with more than 1 file, which is a little scary.

I'd be interested in hearing from people with experience using DW with a SAN.

[ngalemmo]

SAN systems have a complete configuration method that is internal to the unit. The type of RAID and how data is distributed across the disk is all handled by the SAN box. Externally it appears as one big disk, so, as your SAN administrator suggested, doing a lot of work to distribute data files on the database side doesn't really buy you anything.

My experiences with SAN, particularly EMC, has been very good. In one case, a place I was at downgraded their disk from EMC SAN to NAS (for cost reasons) and there was a very noticeable increase in query times (approximately 15-20% slower).

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