VT8237 SATA + RAID

VT8237 SATA + RAID

[Ludwig Meyerhoff]

Hallo!

I wanted to install a new low-usage linux-server, so I bought a 
mainboard with a SATA RAID controller (VT8237) onboard.

I know there are better solutions like RAID controllers with their own 
microcontrollers, but as I only wanted to mirror the data, a "BIOS RAID" 
should do, too.

So I have two 250GB SATA drives, a configured RAID and a Debian 
Netinstall CD (2.6.8-10 kernel). My problem is the "sata_via" module 
loads but does not recognize the RAID function, as instead of one drive 
it finds two.

Googling around I found many people sharing my problem but no one having 
a solution which does not consist of a software-raid managed by the 
kernel (I had some trouble with it when one of the two disks (RAID 1) 
crashed - all data lost).


There seems to be a driver at viaarena.com, but it looks like if it were 
only for 2.4 kernel.



To me it looks like if the sata_via driver lacks the BIOS support, so I 
ask You whether this is the case and what I can do.



Saluti!

Ludwig Meyerhoff

P.s.: I did not subscribe to the list, so please do not forget to cc me 
in replies!

Re: VT8237 SATA + RAID

[Stefan Smietanowski]

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Ludwig Meyerhoff wrote:
> Hallo!
> 
> I wanted to install a new low-usage linux-server, so I bought a
> mainboard with a SATA RAID controller (VT8237) onboard.
> 
> I know there are better solutions like RAID controllers with their own
> microcontrollers, but as I only wanted to mirror the data, a "BIOS RAID"
> should do, too.
> 
> So I have two 250GB SATA drives, a configured RAID and a Debian
> Netinstall CD (2.6.8-10 kernel). My problem is the "sata_via" module
> loads but does not recognize the RAID function, as instead of one drive
> it finds two.
> 
> Googling around I found many people sharing my problem but no one having
> a solution which does not consist of a software-raid managed by the
> kernel (I had some trouble with it when one of the two disks (RAID 1)
> crashed - all data lost).
> 
> There seems to be a driver at viaarena.com, but it looks like if it were
> only for 2.4 kernel.
> 
> To me it looks like if the sata_via driver lacks the BIOS support, so I
> ask You whether this is the case and what I can do.

BIOS raid is nothing more than software RAID. So what you're really
asking here is how you can run software (kernel driven) RAID without
it being driven by the kernel.

It's like asking how you can drive your car that runs on normal petrol
without using petrol.

dmraid might help you out but regardless of how you look at it you'll
always be using the in-kernel RAID support.

Before you ask, how windows does it is simple - they include
software RAID into the windows driver itself instead of using the
built in Windows RAID support.

Or as my mother normally says it "no matter how you turn your ass
is behind you".

BIOS Raid == Software RAID.

If you don't want to use Software RAID you need a hardware RAID card.

// Stefan
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Re: VT8237 SATA + RAID

[Mark Hahn]

> I know there are better solutions like RAID controllers with their own 
> microcontrollers,

the microcontroller is usually orders of magnitude slower than the host,
so "better" does not apply.  offloading parity makes a certain amount 
of sense, but it becomes nontrivial where you draw the line (if you have 
a parity engine, it's nice to have a substantial cache.  if you have a 
big cache, you have to add more smarts in managing it -> TCQ -> pretty
soon you have a full blown SAN raid controller (and the mediocre performance
that implies.)  I think it's mainly marketing pressure that drives people
away from the wisdom of simple-is-better.

> a solution which does not consist of a software-raid managed by the 
> kernel (I had some trouble with it when one of the two disks (RAID 1) 
> crashed - all data lost).

don't be silly - md raid is used in probably tens of millions of servers 
and is not flakey.