Raid question
- Thread starter gary996
- Start date
Depends on the RAID level and card type really.
In general motherboard based controllers are fine for RAID0 or RAID1, normally they're on the south bridge or PCI-e bus so there's rarely a bandwidth bottleneck. For any parity based RAID level (3,5,6 etc) then an add in card with an onboard controller chip is vital as handing off the XOR calculations to the CPU will severly reduce write performance, as happens on mobo based RAID5 controllers.
The problem with add-in cards though is that they can be bandwidth limited, PCI is limited to 133Mbps and can be easily saturated by an array of quick disks. 64bit PCI-X cards are a popular way round this but boards for them are expensive server products. PCI-e cards are coming with 4x and 8x cards providing plenty of bandwidth at reasonable cost for SATA arrays.
In general motherboard based controllers are fine for RAID0 or RAID1, normally they're on the south bridge or PCI-e bus so there's rarely a bandwidth bottleneck. For any parity based RAID level (3,5,6 etc) then an add in card with an onboard controller chip is vital as handing off the XOR calculations to the CPU will severly reduce write performance, as happens on mobo based RAID5 controllers.
The problem with add-in cards though is that they can be bandwidth limited, PCI is limited to 133Mbps and can be easily saturated by an array of quick disks. 64bit PCI-X cards are a popular way round this but boards for them are expensive server products. PCI-e cards are coming with 4x and 8x cards providing plenty of bandwidth at reasonable cost for SATA arrays.
It really depends on how "heavy" your array is. If it is a small array which doesn't see constant activity all day long, then there isn't much difference between an on-board controller and PCI card.
However, when your array gets larger and sees more action you can easily be bottlenecked by a PCI card due to the speed of the data bus.
Either way there are pros and cons to both and what you go for depends what type of array you are using and for what purpose.
SiriusB
However, when your array gets larger and sees more action you can easily be bottlenecked by a PCI card due to the speed of the data bus.
Either way there are pros and cons to both and what you go for depends what type of array you are using and for what purpose.
SiriusB
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it would be onboard RAID0 because im all out of pci and pci-e bays
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ignore that....wrong thread..my bad sorry
ok thanks for that info. It would be niced to see a 64 bit pci-x slot on the new gen boards. They already cost loads without it. Then we have the problem of the amount of room thats on the mobo. Need larger boards more slots
You won't find many consumer motherboards with PCI-X slots. I think even on server motherboards they are only there for legacy these days (like PCI on consumer boards). PCI-E offers superior bandwidth over PCI-X so there's no need for it in the desktop.
The problem is with add-in card manufacturers. A lot of them have been slow to switch over to PCI-E.
The problem is with add-in card manufacturers. A lot of them have been slow to switch over to PCI-E.