Raid, PCIe + Onboard?

[Fineghal]

Situation: I want to create a 5 disk raided storage server.

Problem: The motherboard has 2 onboard Sata connectors.

Since I'm planning on using software raid, it doesn't make a lot of sense for me to drop 300+ on a 8 port sata card I'm just going to be using for just the ports.

Would there be problems if I, for example used 2 PCIe x1 2 port + my onboard for 5 total sata ports?

Should I be concerned about bus saturation?

 

[Czar]

dont think you can have one raid5 array span accross two controlers, but... one way to find out

 

[masteraleph]

I would be very, very nervous about running RAID 5 between multiple controllers (which can be done, though it's definitely a question whether your onboard/cheap PCI-Ex1 controllers will support it).

I haven't seen the numbers, but if you were thinking RAID 5, keep in mind that you only have one disk as failure tolerance- if another goes down while you're rebuilding you'll lose the whole array.

The one thing you don't have to worry about is bus saturation. PCI-E is different from PCI and doesn't share lanes in the same way. If you use a PCI-E 1x slot you're using a PCI-E 1x slot with PCI-E 1x capabilities, period- there's no combined maximum throughput for the bus like there is for PCI.

 

[Madwand1]

It should be fine with OS software RAID. This is one of the benefits of OS RAID -- it doesn't care about the controllers beyond needing basic driver support.

There could be a bottleneck if your on-board storage controller happens to be bridged through PCI, but that's not common for a primary controller.

BTW, Windows Server RAID 5 write performance is generally poor. Linux should be better.