Tablespaces on a raid configuration

PostgreSQL 9.0.x

When PostgreSQL  storage is using a relatively large raid  5 or 6 array is there any value in having your tables distributed across multiple tablespaces if those tablespaces will exists on the same raid array?  I understand the value if you were to have the tablespaces on different raid arrays.  But what about on the same one?

Thanks,

Lance Campbell

Software Architect

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