Subject: Re: PCI Raid controllers
To: Mark Randelhoff <>
From: None <>
List: netbsd-users
Date: 07/15/2004 00:55:06
Mark Randelhoff wrote:

> Hi
> Please would someone recommend a fairly recently released PCI SATA 
> (hardware) raid controller.
> I am looking for a controller that will support up to 8 drives.
> I have tried the 3ware Escalade 9000 series and found that NetBSD does 
> not support it. The local vendor no longer supplies the 8000 series 
> controllers as they appear to be end of line. (I tried adding the pci 
> ids for the 9000 but still would not work). There is a FreeBSD driver 
> for the card and I have looked at porting it - but frankly - I am out 
> of my depth here. Is anyone planning to integrate a driver for this 
> card in the future ??
> I have tried an LSI Logic Megaraid 150-4. This model only offers a 4 
> or 6 drive option. I have also found that the actual card I have will 
> not support past 130G drives. I am testing with 2*400G Hitachi's. I am 
> awaiting confirmation from the vendor that there is a bios upgrade to 
> address this problem - since it sounds like it is the standard 48 bit 
> addressing problem. This card is also a little old.
> I have seen mails warning about the promise raid controllers. Do these 
> warnings still hold ?
> thanks
> Mark
Well I have Promise FastTrak 100-Lite RAID Controller integrated into my 
motherboard, it seems to be supported by NetBSD-2.x but in practice it 
is unusable. Whenever I used it, my system would freeze totally under 
heavy I/O, at least on my system.
You don't say much about what sort of RAID setup you're going to 
implement, if you go for maximum performance and do something like 
striping over 4 or 6 hard disks, then you need to think about the 
bandwidth limits on a PCI bus etc. If you have a 33MHz PCI bus, then a 
maximum theoretical bandwidth would be around 133 MB/sec, with 6 striped 
hard disks, each capable of 40 MB/sec it is easy to saturate your PCI 
bus, which means you won't get the full 6 x 40 = 240MB/sec badwidth. 
Also I've been told that current NetBSD kernels have limits which limit 
the total bandwidth of a RAID subsystem, even though the hardware may 
have plenty of bandwidth.