Adaptec AIC-79xx HostRaid

Adaptec AIC-79xx HostRaid

[Clemente Aguiar]

Hello,

We have acquired some IBM xServers which have an integrated raid controller
based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).

Is there already support for HostRaid? Are there drivers for it?
>From which kernel version and where do I find it in the config?

I would really appreciate any help.

Thanks in advance,
Clemente

Re: Adaptec AIC-79xx HostRaid

[Jeff Garzik]

On Mon, May 30, 2005 at 06:13:03PM +0100, Clemente Aguiar wrote:
> 
> Hello,
> 
> We have acquired some IBM xServers which have an integrated raid controller
> based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).
> 
> Is there already support for HostRaid? Are there drivers for it?
> >From which kernel version and where do I find it in the config?

HostRaid is just software RAID; you can ignore it and let Linux use the
underlying SCSI devices via the standard aic79xx driver.

	Jeff

Re: Adaptec AIC-79xx HostRaid

[Jeff Sipek]

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On Mon, May 30, 2005 at 01:21:05PM -0400, Jeff Garzik wrote:
> On Mon, May 30, 2005 at 06:13:03PM +0100, Clemente Aguiar wrote:
> > 
> > Hello,
> > 
> > We have acquired some IBM xServers which have an integrated raid controller
> > based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).
> > 
> > Is there already support for HostRaid? Are there drivers for it?
> > >From which kernel version and where do I find it in the config?
> 
> HostRaid is just software RAID; you can ignore it and let Linux use the
> underlying SCSI devices via the standard aic79xx driver.

As far as I know, it is software raid done much closer to the hw than
the linux sw raid (md).

There is a module (binary only) from Adaptec that lets Linux use HostRaid,
but from what I saw, it just worked with RHEL 3.x and some other ancient
RH releases. When I was installing RHEL 4 on an IBM xServer, I decided to
just do standard linux sw array.

Jeff.

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Re: Adaptec AIC-79xx HostRaid

[Jeff Garzik]

Jeff Sipek wrote:
> On Mon, May 30, 2005 at 01:21:05PM -0400, Jeff Garzik wrote:
> 
>>On Mon, May 30, 2005 at 06:13:03PM +0100, Clemente Aguiar wrote:
>>
>>>Hello,
>>>
>>>We have acquired some IBM xServers which have an integrated raid controller
>>>based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).
>>>
>>>Is there already support for HostRaid? Are there drivers for it?
>>>>From which kernel version and where do I find it in the config?
>>
>>HostRaid is just software RAID; you can ignore it and let Linux use the
>>underlying SCSI devices via the standard aic79xx driver.
> 
> 
> As far as I know, it is software raid done much closer to the hw than
> the linux sw raid (md).

software RAID is software RAID.

It makes no difference whether you embed the RAID software in the 
Adaptec driver or make it a separate module.

	Jeff

Re: Adaptec AIC-79xx HostRaid

[Clemente Aguiar]

>On Mon, May 30, 2005 at 06:13:03PM +0100, Clemente Aguiar wrote:
>> 
>> Hello,
>> 
>> We have acquired some IBM xServers which have an integrated raid
controller
>> based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).
>> 
>> Is there already support for HostRaid? Are there drivers for it?
>> >From which kernel version and where do I find it in the config?
>
>HostRaid is just software RAID; you can ignore it and let Linux use the
>underlying SCSI devices via the standard aic79xx driver.
>
>	Jeff

What do you mean it is just software RAID? Can you explain?
On the servers there is a configuration option to enable HostRaid, and when
I turn that option ON the mirroring between the two discs start and after a
while they are mirrored.
I think that in terms of performance it should be better to used the
"on-board" HostRaid facility.
Don't you think so?

Clemente

Re: Adaptec AIC-79xx HostRaid

[Jeff Garzik]

Clemente Aguiar wrote:
>>On Mon, May 30, 2005 at 06:13:03PM +0100, Clemente Aguiar wrote:
>>
>>>Hello,
>>>
>>>We have acquired some IBM xServers which have an integrated raid
> 
> controller
> 
>>>based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).
>>>
>>>Is there already support for HostRaid? Are there drivers for it?
>>>>From which kernel version and where do I find it in the config?
>>
>>HostRaid is just software RAID; you can ignore it and let Linux use the
>>underlying SCSI devices via the standard aic79xx driver.
>>
>>	Jeff
> 
> 
> What do you mean it is just software RAID? Can you explain?
> On the servers there is a configuration option to enable HostRaid, and when
> I turn that option ON the mirroring between the two discs start and after a
> while they are mirrored.
> I think that in terms of performance it should be better to used the
> "on-board" HostRaid facility.
> Don't you think so?

HostRaid is not on-board.  It is provided by your system CPU, through 
the card's BIOS and the OS driver.

HostRaid is software RAID, just like Linux's md.

	Jeff

Re: Adaptec AIC-79xx HostRaid

[Eric Jones]

 >>>We have acquired some IBM xServers which have an integrated raid controller
 >>>based on the Adaptec AIC-79xx U320 SCSI controller (called HostRaid).
 >>>
 > As far as I know, it is software raid done much closer to the hw than
 > the linux sw raid (md).

Actually, there are two possible configurations, depending on HW configuration...

For example the IBM x346 server has an onboard Adaptec 7902 SCSI controller chip for the
U320 backplane devices (max-6 devices). This chip uses the standard aix79xx driver for
normal SCSI functions.  But, for extra $$$, you can also buy the IBM feature "ServeRAID-7k"
which is a small DIMM-sized plugin module that adds XOR parity generation and a small cache.
 
http://www-132.ibm.com/webapp/wcs/stores/servlet/ProductDisplay?productId=8735579&storeId=1&langId=-1&catalogId=-840 


Adaptec calls this a "zero-slot" RAID solution, and it requires a special binary driver
to recognize and handle the array functions.


Most people seem to order this bit with the initial kit, but then rip it out when they realize
it needs a binary driver to support the RAID functions.  The Linux SW-RAID seems to provide
better IO performance, and you can still see the individual sdx devices on the SCSI bus.
This makes it easier to monitor device performance and health (ie. smartd, etc), vs the Adaptec
"Hide everything behind the controller" approach with the ServeRAID-7k configuration.


Eric

Re: Adaptec AIC-79xx HostRaid

[Arjan van de Ven]

>  But, for extra $$$, you can also buy the IBM feature "ServeRAID-7k"
> which is a small DIMM-sized plugin module that adds XOR parity generation and a small cache.
>  
> http://www-132.ibm.com/webapp/wcs/stores/servlet/ProductDisplay?productId=8735579&storeId=1&langId=-1&catalogId=-840 
> 
> 
> Adaptec calls this a "zero-slot" RAID solution, and it requires a special binary driver
> to recognize and handle the array functions.

I would be very suspicious about the claim that the xor stuff is done in
hardware and not in the binary part. I'm actually surprised that a linux
friendly company like IBM actually gets involved with binary drivers
like this though.... a bit disappointing.

but yeah this sounds like a really bad purchase.

Re: Adaptec AIC-79xx HostRaid

[Robert Hancock]

Arjan van de Ven wrote:
> I would be very suspicious about the claim that the xor stuff is done in
> hardware and not in the binary part. I'm actually surprised that a linux
> friendly company like IBM actually gets involved with binary drivers
> like this though.... a bit disappointing.
> 
> but yeah this sounds like a really bad purchase.

Indeed, this controller in the 346s is a regression from the 345 
servers, which had an onboard LSI Logic Fusion MPT controller which 
could do hardware RAID 1, at least, and has a GPL driver.

Oh well.. if you really want to use hardware RAID, you can put in the 
ServeRAID-7k card, which is much better, and has a GPL driver.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/