Storage RAID Array Using PCI card and motherboard connectors

Hi guys,

I'm currently building a media server at home and I'm looking into using RAID 5 to help provide some performance gains/continuation as well as some redundancy.

I thought my mobo supported it natively ie in the bios (Asus P5B) however upon looking closer I don't think it does.

So I need to get a PCI card to do it for me.

This leads me on to my question, can the PCI card use SATA connections that are on the mobo as part of the array? I'm accumulating drives slowly and given that most reasonably priced RAID cards only support 3 + 1 eSata connection I find that quite limiting. I was hoping the card would be able to access mobo ports as well to include in the array. Is that right?

Regards,

Chris

 

I think it has to use the Sata ports on the PCi card it's self.

How may ports do you think you will need?
Be careful with the cheaper PCI cards as they usually don't support raid 5

 

To be honest I don't know how many I will need, I've got about 4 drives at the moment all with data on. So I was hoping I could use them, and just keep expanding the array as I need to.

I'd certainly prefer it to be that way, rather than have to scrap my drives and replace them all with say 2 TB drives. It seems daft that if you want to expand the array you need to replace all the drives with higher capacity etc.

The cards I've seen are in the £40-£50 area - although I've seen some in the several hundred!

 

I don't think any card in that region would support raid 5.
Although I'm no expert. Hopefully somebody else will come along and fill you in.

 

http://www.lambda-tek.com/componentshop/index.pl?origin=gbase5.5&prodID=B463968

Found this through google shopping ... theres quite a few around the same price.

So is the general consensus that the PCI card won't be able to exploit mobo sata connectors as well for the array?

 

What software will you be using on your media server? Does it do software RAID e.g. FreeNAS or unRAID?

These are cheaper: http://linitx.com/viewproduct.php?prodid=11624 but are SATA I and are not RAID cards.

 

To be honest I was hoping to use linux so it could be a general server (as in the build your own server guide on bit tech) but then I also want it to be a media server (as in the build a dvd server guide also on bit tech) but I didn't want to use unRAID as that mean's I wouldnt be able to "use" the machine for anything else other than storage - I'd like to be a functional pc. Rather than behaving like a NAS box.

I've just had a thought, using linux, would it be possible to use software to drive a RAID array? I've heard the phrase s/w raid pop up a few times.

EDIT: Further reasons for a general linux (Xubuntu) install also come from :

a) Want to use it to fold
b) Want to install Steam on it so I can use it as a gaming server

 

The bandwidth for the entire PCI bus is 127.2 MB/s (33MHz), or 508.6 for 64 bit PCI (66MHz). So all the devices on the bus would have to share this bandwidth. I'm not sure but I think most cards/interfaces tend to be the 33MHz variety, A single F3 disk would come close to saturating this in normal use and be limited by it when it does buffered sequential reads and writes.

If this is the case then more than fast one disk on the PCI card wouldn't really give you much advantage. If you were only to use one disk on the PCI bus and the rest on your motherboard, or even all on your motherboard then if you decided to go with windows you could use Dynamic disks to create a software Raid 0 or Raid 1 setup, not used it in a while so not sure if they developed it to include raid 5.

Also I seem to remember having booting problems with dynamic disks enabled and having to have my OS's on a seperate simple volume. This may have just been because I was using multiple versions of windows though.

 

The bottleneck will be the NIC speed, not the disk or bus I/O.

 

Good point, even Gigabit is 100MB/s most normal network with Cat5 cabling is only 10MB/s so raid is only going to cost you more, might as well just get the best speed/value/size single disk(s)

 

If you *really* want to go the RAID route, you want to spend money on a proper hardware RAID card that peforms the processing on its own embedded chip. I was lucky enough to nab my LSI 8708 on ebay for just £125 instead of its £430 RRP. It offers 8 ports, PCIe connectivity (PCI is too slow tbh), RAID 0/1/5/6 and various nifty features like online RAID level migration and online RAID array migration (so you can start with the drives you have, then replace them one-by-one with 2TB drives while your data stays fully accessible).

If you can't use a PCIe interface, or can't justify the outlay on a full hardware RAID card, just turn back and return to single drive land. You'll avoid a ton of headaches that way.

 

Totally agree with this, I have a Dell Perc 5/i which are fantastic and can be picked up for cheap on ebay (around £100). Put that in a second PCI-E slot, get 4 cheap 500gb hard disks in raid 5 and you'll have some seriously nice speeds.

 

If he is purely connecting to the server over Gbit ethernet, surely any speed increase due to an expensive hardware RAID controller will never be noticed?

Surely software RAID is a better budget option?

 

Well, a software RAID 5 card will put a fairly significant burden on the processor for starters, especially when writing data.

The OP also speaks of moving to larger capacity drives in future - migrating seamlessly is only possible with hardware RAID. Otherwise, it'll be a laborious process of backing everything up to external storage, breaking the array, replacing the drives, creating a new array and then restoring the data to the new array.

The upshot is that beyond a simple RAID 0/1 setup, it's not something I can recommend in good faith.

 

Interesting comments there guys thanks very much...

If I could track down a PCIe card that had RAID 5 and 8 ports like previously mentioned ... would it have the capacity to be able to exploit the mobo sata ports as well, or is it purely limited to its own?

Having said that, if it has the ability to be so easily expanded and augmented (swapping drives) and 8-port card should be the dogs.

 

I expect it would use it's own

 

I haven't seen any cards that will utilize the on-board ports as part of a RAID Array.