There are plenty of disk controllers on the market that don't do well at database tasks. Here are a few products that are known to work well with the sort of hardware that PostgreSQL is deployed on:
- LSI's MegaRAID line has been a source for reliable, medium performance SCSI, and now SAS/SATA, controllers for many years. They tend to have smaller cache sizes and their older products in particular were not always the fastest choice available, but their technology is mature and the drivers you get tend to be quite stable. The current SAS products perform extremely well in RAID 10, the usual preferred topology for databases. Its RAID 5 performance is still not very impressive.
- Dell has offered a rebranded LSI MegaRAID ...
