Sata RAID Controller - What to buy?

I wouldn't know the specifics/performance of each of those cards, but as a rule of thumb, if you are serious about RAID:

-a decent card no matter what brand should cost about 250USD minimum and upward. cheaper cards may not be that reliable and may not provide such great compatibility ie divers for windows only.

-look for a card that has a dedicated processor and ram cache. As with the above point, many cheaper cards (under 250) will look fancy, have multiple ports and even have a ram cache, but will lack a dedicated processor, so will offload the processing onto the main cpu. this may not be a problem if you have a quad core or similar though.

Having said all that, I assume when you say mirror that you mean RAID1 which doesn;t require much "processing power." So in this case you may get away with a cheap one. However, I would still go for a more upmarket one due to the better quality and future expansion options.

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BTW, avoid the rosewill...