[CentOS] Centos 4.4: Support for Dell PowerEdge 830 CERC 6-Channel SATA RAID Controller

[Erick Perez]

Rodrigo, as always
A BIG THANKS!!!!!!!!


On 9/14/06, Rodrigo Barbosa <rodrigob at darkover.org> wrote:
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> Note: There IS an authoritative answer on this e-mail. Be patient with
> me, please :)
>
> On Wed, Sep 13, 2006 at 11:14:20PM -0500, Erick Perez wrote:
> > Does Centos/RHEL 4.4 supports the CERC 6-Channel SATA RAID Controller
> > that comes with the Dell PowerEdge 830 Tower Server?
>
> CERC meaning "Cost Effective Raid Controller", which doesn't bode well.
>
> According to Dell[1]:
>
> [QUOTE]
> CERC SATA 2S
>
> The CERC SATA 2S RAID controller is a combination BIOS and driver-based
> software RAID solution, which uses the system motherboard's SATA controllers.
> It is not a hardware RAID solution such as the aacraid and megaraid
> controllers listed above.
>
> Systems with this controller include the PowerEdge 800, SC1425, and 420SC.
>
> Under Windows and Netware, there are special device drivers which operate in
> conjunction with the system BIOS to present the system SATA disks as a RAID
> volume.
>
> Under Linux, the disks should be treated as two independent disks, which use
> the standard Linux "MD" software RAID layer for RAID 0 or 1 operation (if
> you so desire). System Documentation on support.dell.com[2] describe how to
> configure the system BIOS to either disable the RAID mode, or to set up the
> disks as two independent RAID volumes (effectively disabling the BIOS software
> RAID feature).
> [/QUOTE]
>
> Notice: "It is not a hardware RAID solution". Also notice this might not
> be the controller you have.
>
> On the other hand, some people claim otherwise[3]:
> "I did some digging this AM and everything points to it being a MegaRAID
> SATA 150-6 card (...)"
>
> You might also take a look, subcribe or ask questions on the
> linux-poweredge mailing list[4]. That might be the best place to
> get help on this issue.
> This[5] particular post seems promising.
>
> This last page[6] seems to indicate that it is really a magaraid-like
> controller, even providing a software to monitor it.
>
> Of course all of that is very instructive, but doesn't give you an
> authoritative answer. Where should we look for that ? The kernel source,
> of course ("Use the source, Luke!").
>
> The file drivers/scsi/aacraid/linit.c can be very instrutive on this particular
> case. On line 136 (or thereabout), you will find:
>
>         { 0x9005, 0x0285, 0x1028, 0x0291, 0, 0, 38 }, /* CERC SATA RAID 2 PCI SATA 6ch (DellCorsair) */
>
> And on line 211 (or thereabout):
>
>         { aac_rx_init, "aacraid",  "DELL    ", "CERC SR2        ", 1 }, /* CERC SATA RAID 2 PCI SATA 6ch (DellCorsair) */
>
>         So we have a CERC SATA RAID with 6 channels from Dell, which really
> looks like the one you are talking about. It gets identified as CERC SR2,
> and is supported bu the aacraid driver. The only question left is, does
> this support exists out of the box on CentOS (4.4) ? Lets ask the module,
> of course. On /lib/modules/2.6.9-42.0.2.EL/kernel/drivers/scsi/aacraid, we
> can check it:
>
> # strings aacraid.ko | grep CERC
> CERC SR2
>
>         There you go. Sorry for taking so much space to answer your question,
> but I'm hoping you can use my reasoning here for other things as well.
>
> References:
> 1 - http://linux.dell.com/storage.shtml
> 2 - http://support.dell.com/support/edocs/systems/SC1425/en/index.htm
> 3 - http://www.linuxquestions.org/questions/showthread.php?t=336615
> 4 - http://lists.us.dell.com/pipermail/linux-poweredge/
> 5 - http://marc.theaimsgroup.com/?l=linux-poweredge&m=112783948009432&w=2
> 6 - http://www.deadcat.net/search.php?action=browse&sectionid=16
>
> - --
> Rodrigo Barbosa
> "Quid quid Latine dictum sit, altum viditur"
> "Be excellent to each other ..." - Bill & Ted (Wyld Stallyns)
>
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-- 
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Erick Perez
Panama Sistemas
Integradores de Telefonia IP y Soluciones Para Centros de Datos
Panama, Republica de Panama
Cel Panama. +(507) 6694-4780
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