phongn wrote:
True enough, but if the write performance is disproportionately slow, it block the database non-trivially.
I think the random read performance benefits would outweigh the hit in write performance, and the overhead on writes is largely exaggerated.
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The above might shed a little more light on this.
Quite a bit of CPU time is offloaded for a "true" hardware RAID controller. I'm not sure if the low-end Promise cards count as one - the drivers, IIRC, are doing all the work there via CPU time. Their higher-end cards, certainly, do 'real' work, but I've usually preferred 3ware for that kind of work.
EDIT: Don't forget that if Mike is forced to use a PCI RAID card, he's going to get a bottleneck from the PCI bus' bandwidth limitations.
I would never use a PCI SATA RAID controller, the PCI-E cards are plentiful and affordable and won't overload the bus.
The Promise SuperTrak EX4350 is a good example of just such a card, and it is also a hardware RAID solution with 64MB of dedicated memory and an onboard RISC processor for parity calcs.
EDIT: Of course this assumes Mike has PCI-E slots on his motherboard. PCI-E x4 of course being the most ideal and a lot of mobos have them, but I'm not sure about his S939 board.
EDIT2: Mike's Asus A8N-E APPEARS to have a PCI-E x4 slot if my eyes are correct.