I like the mono of my test & backup server as it is fast enough and provides VT-D support. However I do need some more capacity and have only 2 PCI slots available.

 

Is there any advise for a 4-port PCI card? Would this be a good choice? http://www.newegg.com/Product/Product.aspx?Item=N82E16816124028&cm_re=SIL3124-_-16-124-028-_-Product

 

Thanks for any advise.

There are 2 issues with these kind of cards.

1. PCI - bandwidth is a bottleneck with >2 modern disks.

If you tend to use 2 controllers @ 4 drives, you imagine,

it won't get any better! All drives will hook on the same bus.

You will have 8 drives sharing 500MB/s transfer speed if you have the latest PCI 2.3 64bit@66MHz.

While not a problem during normal operation, this is not very nice during the regular parity check.

 

2. Check if the controller supports drives with capacity >2.2TB

 

Here is our controller database.

There are already some Syba controllers known working.

Most motherboard PCI only provides for 133 MB/s, so if you only put two drives on the PCI bus you will be limited to maximum 66 MB/s in parity check, parity build, and drive reconstruction scenarios. If you put 4 drives the maximum speed would be 33 MB/s. In reality, your speeds will be LESS than that.

 

Do NOT use PCI unless you don't value your own sanity.

Thanks a lot to both of you - I have to live with the 6 SATA II ports then.

You can add more drives but not more than 2 for the use with unRAID.

 

You can add more than 2 if you want to have an additional cache drive or something similar that is not

involved in the regular parity check.

 

With regard to that controller, you should check if it supports huge drives!

 

A bit of counterpoint => if you NEED the additional space and aren't ready to upgrade the server, then using PCI controllers may not be such a bad thing.    In normal use, when you're only writing to a single drive, then you'll get plenty of bandwidth for the single drive that's in use (as long as the parity drive is on a motherboard controller port).

 

The only really major slowdown will be with parity checks and rebuilds ... when ALL of the drives on the controller are being accessed at the same time, effectively slowing the entire array down a LOT.    If you can live with the long parity check/rebuild times, an inexpensive PCI controller is fine as a temporary work-a-round to provide more capacity.

 

... but if your current drives are relatively small, a better approach is to replace them with higher capacity drives and maintain the higher speeds of the motherboard ports.

 

Thanks a lot for your advise. I will keep my test&backup environment as simple as possible and will not install any additional controller. I will go with larger disks instead but I appreciate the different views that you all came up with.