One configuration I looked at included:
The second configuration was the same as above with 4 TB HP EVA5000 system combination FC drives and FATA drives managed by the OS.
The OS managed system sounds good, but are the FC and FATA drives a two-tier solution or is it just 4 TB of storage, with no way to enhance performance or load balance?
As for flexibility and performance, you can configure different RAID types within the arrays to match the applications requirements. RAID-1 or RAID-10 is best for log file storage, and RAID-5 can house database-type storage. This would give you both two tiers of performance and two tiers of storage classes. Load balancing would be done at the host side using the path failover software. If you use volume management on the host side, you can stripe your LUN access across both HBAs for best performance.
You mentioned 16 port switches. Since you also said your growth within the next two years would almost quintuple your requirements (from 4 to 30 TB, and addition of Unix and VMS servers), I would start out with more ports in the switches (Perhaps dual 32 port switches). If your budget does not allow for larger switches, then make sure the ones you buy will support zoning and trunking. As the SAN grows and you add more switches, you don't want to have to include multiple hops and many ISLs (inter-switch links). Moving to larger CORE type switches may be a better way to grow. Also note that Unix, VMS and Windows servers should be placed in separate zones within the fabric.
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