Buying Raid Card - Questions

[DrasticTactics]

I have two Ultra ATA drives that I need to setup raid 1 on, for backup purposes only.

I have heard good things about promise, so I was thinking about getting the FASTTRAK TX2000.

I also noticed the new S150 TX2+ (two sata ports, 1 ultra ata port).

So I was wondering if I should go with the s150 for furture SATA compatibility. However, I don't know if running both Ultra ATA drives on the same channel/port would hinder the Raid 1 performance or not, which is how I'd be using the card for now.

Does Raid 1 performance take a hit with both drives on the same port/channel?

Do you have a better suggestion for a Raid card for what I need? (Just need it for 2 drives, just for Raid 1 for backup only)

 

[Lord Evermore]

It will hinder performance. Only one ATA device can be active on a channel/cable at one time. Read through Promise's docs, they mention that, and it's why they have the TX4 for people with 4 drives.

Since the mirror results in both drives having to have the data written to them, a duplicate bit of data gets written to each one in an alternating sequence. So you get performance less than that of a single drive for writes. Generally write speed is a little slower with mirroring anyway, but it'll be worse with them both on one channel. Reads won't get any performance loss I expect, since the read can come from only one drive, however that depends on Promise's design. In normal RAID1, a read comes from both the drives to nearly double the read speed (each drive reads half of the needed data). Since they can't both read at the same time, if the drivers and controller don't avoid the read from both drives, you end up again with only the performance of a single drive or less.

RAID0 would see the same performance loss if they were both on one channel.

The controller though most likely lets you set up one drive on the regular port, and another on an SATA port and run RAID that way. You could get an adapter for one of the drives to use the SATA port, but of course there might be slight performance differences. Or you could use two adapters so they're both SATA, but that'd run 40 or 50 dollars just for the adapters.

I don't really think you need to be concerned with future use of the card. The expense isn't that great if you do need an SATA RAID card in the future, and it's too much of a hassle trying to set it up with a mixed controller like this. Pretty much any RAID card will do the job you want to do. I think the TX2000 is a hardware controller, while most are software controlled, the chip just providing an interface to work with like a soft-modem. Based on the popularity, it doesn't seem like it's a significant loss of CPU power to deal with it.