jonalberghini (5/1/2012)
I have a question. Everyone talks about Raid levels and performance but what about performance in terms of the number of logical luns? Is it better from a pure performance stand point to show say 8 LUNS to Windows Server as oppsed to one large LUN? I know it is bound by the number of actual spindles but I was under the impression that more LUNS is better. I know it is harder from a maintainane stand point. But since Windows Server see it as a physical disk. can it more efficiently utilize the large SAS pipe. My raid setup has 5 drive in a RAID1 setup. They are 15,000 RPM600 gig drive with a SAS 6g pipe. I show one Logical LUN would I get better performance if I showed 4 LUNS. Can Windows have more outstanding requests?
Thanks
Pleas help.
This will completely depend on how you are accessing the LUNs. If you are accessing all of the LUNs over the same path, then you are gaining on your restore capabilities as you can choose which disk to restore first as you have for instance 5 - 300GB drives presented to the OS vs 1 1.5TB drive. This means for much more granular recovery ability. If you are able to do parrallel access of multiple LUNs then it would make sense to do multiples as, like another poster mentioned, we often move our performance bottleneck from Disk to HBA Port, Fibre Switch, Cache ability etc. It really comes down to being in Lock Step with your hardware vendors and with your system design folks to ensure that the system is corretly layed out from end to end to meet its purpose.
All to often we get the parties involved saying 'What do you need' when in fact a roundtable discussion of experts in each area is required to ensure that we don't add a simple bottleneck to an extremely robust high performing solution thus negating 10's of thousands of dollars in investments.