it's time for a (partial) hardware replacement and our company decided to provide a SAN as a replacemenet of the dedicated drives of let's say 10 server with two drives each, originally.
To be specific: there'll be only one rather small drive per server just to hold the OS and the pagefile, eventually. (I say "eventually" since the the folks responsible
for the sizing decided to use a standard config of less than 50GB, regardless of the servers memory. My question how they would provide a full memory dump for a server with 256GB memory in case of a support request to MS is "still under investigation"... but that's a different story).
The SAN will have 15 spindles in total and RAID0, RAID1, and RAID5 groups.
There will be about 50 SQL Server DBs (ranging from just a few MB up to 80GB) as well as several applications.
If I'm not completely wrong there'll be only max. 7 spindles net to hold all the LUNs (based on the RAID level and the physical number of spindles).
Even though the total size of storage capacity is enough to meet our needs, the number of physical spindles seems to be too low. From my perspective the better disc performance (e.g. 15krpm vs. currently 10krpm) will not compensate the parallel access from several server to the same spindle(s).
My question "Why not reduce the disc size in favor of more spindles?" has been answered with "The discs we've chosen are based on the lowest cost per GB and the best performance." I suggested to at least increase the local disc size to have TempDb stored locally (on a separate logical drive), but so far without any luck...
Am I worried for no reason?
Edit: I'm planning to "attack" the SAN using SQLIO concurrently from several servers prior to going into production to verify the performance metrics they've told us.
A pessimist is an optimist with experience.
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