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Linux support for onboard Raid?

A

arib0nd

Member
I was looking into buying a KT333 mobo with onboard raid on it. Most of these seem to have the Promise 20276 as the onboard raid controller.

Does anyone know if Linux supports it? I was thinking of putting two hard drives in there and booting off them using Raid 1 (yea Raid 1 not Raid 0).

Thx
 
Um thats for a Promise FastTrak.. thats not what u get onboard most mobo's.

As far as I can see from downloading the kernels.. the 2.4.19 or even 2.4.20-pre7 doesnt have support for Promise 20276 .

But the 2.5.37 kernel does.. so I guess Iw ill have to run a 2.5.x kernel on another one of my machines.. sigh..

I already have to run it on one of my computers, since the 2.4.19 doesnt support my netgear copper Gigabit card..

damn.
 
The linux IDE site claims that the 20276 is supported, and I read elsewhere that 2.4.19 should have it. You said you checked, but perhaps the kernel help file wasn't updated?

And the Fasttrak support *is* what you want - the onboard version is the Fasttrak Lite, but it's identical as far as kernel configuration is concerned. The "Promise PDC202{47|65|67..." option is only for using the Promise controller as a regular IDE controller. That much I know, because the system I'm typing from is running on an onboard 20265 RAID 1 array, and I have only the later, "Promise Fasttrak" option enabled in my kernel config - not the generic Promise PDC202* chipset support.

And if for some reason all that doesn't work, you could always snag a plain ATA100 promise card and do software RAID.
 
CONFIG_BLK_DEV_ATARAID:

Say Y or M if you have an IDE Raid controller and want linux to use its softwareraid feature. You must also select an appropriate for your board low-level driver below.

Note, that Linux does not use the Raid implementation in BIOS, and the main purpose for this feature is to retain compatibility and data integrity with other OS-es, using the same disk array. Linux has its own Raid drivers, which you should use if you need better performance.
Click to expand...

Thats what the 2.4.19 kernel help says.. So firstly it seems to imply that I have to enable this in the kernel.. in addition to enabling support for ""Promise PDC202{47|65|67..." . It is entirely possible that those drivers even support the 20276, but I can't know that for sure till I have the mobo.. but I dont wanna buy a mobo with onboard raid, if I am gonna have to buy a stand alone card anyway.. so its kind of like a chicken and egg problem..

Also as I had read earlier, and this helpfile reaffirms, Linux has much better performance if I were to just compile the Promise support as a ide controller, and then let Linux do software raid on it, rather than using the Fasttrak support in the kernel, which supposedly has better performance, but would be better if I wanted to maintain data integrity and compatibility with other OS's..b ut I dont plan on dual booting. either its gonna work in linux, and thats it.. else I am gonna have to throw win2k on there.

Can you possibly check to see how your machine is configured? coz the Kernel Documentation seems to contradict what u r saying, but then again.. u cant trust the docs too much..

But I also found the following from the linux Ide site.. yes it does claim support for the 20276, but I wonder which kernel they mean supports it.. But also found a link off the site.. http://people.redhat.com/arjanv/pdcraid/ataraidhowto.html
This is what it says...
This document describes how to use the RAID on IDE raid controllers with a Linux system using a 2.4 kernel, using nothing but Open Source software. Currently, only RAID level 0 (striping) is supported, for the Promise Fasttrak(tm) and Highpoint HPT370 series of IDE RAID controllers.
Click to expand...

So another question.. are u using raid 0 or 1?

Thx.

Ari
 
OK, first of all, I was an idiot and said RAID 1. I'm running RAID 0. Hope you didn't destroy anything yet. 🙂 I'm looking around a bit. Be back soon.
 
Goddamn, now I remember how confused I was when I researched this last year. Everybody says something different. It's really quite simple once it's set up though. Some comments, in no particular order:

1) As stated before, I'm running RAID 0. But the LDP ATA-RAID HOWTO author is quite clearly using the ataraid driver to run RAID 1. Presumably, they added RAID 1 support later. Arjan's HOWTO is quite dated, you may notice. Could be that RAID 1 requires a bit different setup, though.

2) My kernel does *not* have the first (CONFIG_BLK_DEV_PROMISE_202xx) chipset option enabled. It does use the IDE RAID and Promise Fasttrak RAID options (CONFIG_BLK_DEV_ATARAID and CONFIG_BLK_DEV_ATARAID_PDC). Like I said before, I think that the first option is for using the Fasttrak as a regular IDE card. But perhaps it's needed for RAID 1 - the LDP HOWTO author enables all three options. Dunno.

3) While the various writers all use initrd, I never have. I still don't understand why it's necessary, unless maybe it's for the case where people want to compile the RAID support as a module rather than statically.

4) I think you're misreading the CONFIG_BLK_DEV_ATARAID help - "choosing a low-level driver *below*" means picking either the Promise or Highpoint specific driver options that appear after you enable the generic ataraid support - not picking the CONFIG_BLK_DEV_PROMISE_202XX option.

5) Like you, I can't really find any hard evidence as to how the 20276 is supported. I found a post on some board a while ago that clearly stated that it was in 2.4.19. Maybe he was full of it. Or maybe it's not in the help file. Or, maybe it's not supported in the 202xx driver, but it is supported in the Fasttrak driver - which doesn't specifically mention its chipsets. So many mysteries...


That's about all I can tell you. This should teach us to get real RAID cards next time 🙂
 
hehe.

Look what I found http://tw.giga-byte.com/support/d_other.htm

if you scroll down, they have downloadable linux drivers for the onboard raid controller I wanna use. the problem is that they seem to be built for redhat , and another for suse.. so i dont htink I can use them..

why cant they just send the driver code into the kernel folks and have them integrate into the damn kernel..

Damn it

 
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