RAID experts and/or Linux gurus

[GL]

I'd like to setup an IDE-based RAID 1 setup on a server I'm assembling. It seems to me that all the IDE RAID controllers save for those that are out of my budget, use the PCI bus. Of course the add-on RAID cards are PCI ones. But even the integrated motherboards seem to just slap a RAID chip onto the PCI bus rather than integrate it into the northbridge.

So, my question is: how much of a performance hit is there running a hard disk off of the RAID host using the PCI bus as opposed to off the other IDE host integrated into the northbridge? I'd suspect there would be scenarios where the PCI bus could run out of bandwidth if it was inundated with data from a RAID array and other devices on the bus.

If it would be mode ideal to run a hard disk off of the northbridge-connected IDE adapter, I was thinking of running the following setup. I would have a software RAID 1 setup in Linux, with two hard drives (one Primary master and the other the Secondary master) connected to the northbridge-connected IDE hosts. How would this compare performance-wise to, say a Promise FastTrak or Highpoint RAID controller setup? Would the benefits of running on the faster IDE host be negated by using pure software RAID as opposed to the Promise FastTrak or Highpoint RAID?

 

[Barnaby W. Füi]

Well the PCI bus is roughly 133MB/s, so I don't think two IDE drives are going to quite soak that up unless you're transferring a ton of stuff and also needing the PCI bus for something else significant at the same time. That's just my speculation though. Hmmmm actually.. the data is only transferred over PCI once, the raid controller then sends it to each drive. So I'd think you should be more than fine.

 

[GL]

Originally posted by: BingBongWongFooey
Well the PCI bus is roughly 133MB/s, so I don't think two IDE drives are going to quite soak that up unless you're transferring a ton of stuff and also needing the PCI bus for something else significant at the same time. That's just my speculation though. Hmmmm actually.. the data is only transferred over PCI once, the raid controller then sends it to each drive. So I'd think you should be more than fine.

I thought that the cheaper RAID solutions (HighPoint and lower-end Promise ones) actually were just normal IDE hosts and performed their RAID functionality via driver tricks. In that case, for a RAID 1 setup, wouldn't there be twice the bandwidth usage for writes? I'm thinking that a couple of modern IDE drives could possibly get near the PCI bus's theoretical peak bandwidth, and that's not taking into consideration that other devices may be on the bus.

 

[mcveigh]

well what are you doing with it?

FWIW I have 3 servers running linux and 3ware raid controllers...I love em

 

[GL]

Originally posted by: mcveigh
well what are you doing with it?

FWIW I have 3 servers running linux and 3ware raid controllers...I love em

I'll be hosting a few moderate-to-low traffic database-driven intranet sites. It'll also act as an IMAP server and backup server. I guess I'm being really picky about this, but I'm more curious about what the answer is than I am concerned that it'd negatively affect the server performance which it probably won't too much.

What I'm thinking of doing is going with an i865G with the ICH5, and putting a couple of Raptors on either SATA bus. Then, I'll just use software RAID 1 in Linux. I think this should perform as well as a Promise FastTrak or HighPoint controller. Perhaps even better.

Those 3ware cards look sweet by the way!