PCI-e RAID Controller vs Built-in MB RAID Controller

OmegaWookiee · February 15, 2018

If a 4 port RAID Controller (SI-PEX40057) supports 6Gbps but is only going through a PCI-e 2.0 x2 port (10GT/s)(8Gbps), wouldn't the built-in RAID controller of a MB be faster even though the MB ports are 4 x 3Gbps? It's an old Intel board (DX79TO) and they won't answer my questions about it.

I can't tell if there is an actual RAID chipset on board, and if so, what it is. From what I read, if there isn't an actual chipset on-board, this the CPU does the RAID management. I'm not looking to increase CPU load, for sure.

Also, there's some concern with loss of power and that the PCIe card will finish it's writes more reliably in that situation.

Oshino Shinobu · February 15, 2018

Kind of depends on the drives you're using and how many ports you're actually using. The motherboard should provide more bandwidth in certain situations and the RAID card will provide more in other situations. If you're using hard drives, it doesn't really matter as they're not going to even use all of the 3Gbps bandwidth from SATA 2.

In general, the RAID card will be the more reliable option. You can actually move the RAID array if you need to and you're not completely screwed if the motherboard dies as you can rebuild the array.

grimreeper132 · February 15, 2018

if you used a RAID card it would be hardware RAID you would use and it would better to a point, but unless you have ran out of SATA ports on your motherboard, and/or you need the faster speeds, the motherboard ones would be fine using software raid. As for the card it's self, get an ex enterprise one off ebay, as you can get a 8 way 6Gbps X8/16 PCIe normally pretty cheaply (you will need special SAS to 4 SATA cables but they cost about £3 each)

Electronics Wizardy · February 15, 2018

Don't ues motherboard raid or cheap raid cards. You know a raid card is good if it has a battery. Both of these solutions seem to use the cpu for raid calculations.

If you want raid your much better off using software raid. Its better at protecting data, faster, easier to manage, easier to migrate.

OmegaWookiee · February 15, 2018

Sounds like the opinions are all over the place. I should have stated I'm doing RAID 10 on 4 x 256GB 6Gbps SSD cards.

So, what I'm hearing is that if I try to use the on-board RAID controller, it may be software based. And, it will probably need to rebuild the array in either case if I don't use the RAID card. I have already used the RAID card because my old board didn't have RAID built in. My old board died so this is my replacement. So since I already have data on the drives, won't rebuilding the array erase everything? Or does it just re-index all the existing data? This is my first RAID.