Re: Installing Linux on RAID

[Robert Citek <rwcitek@alum.calberkeley.org>]

On Tuesday, Sep 28, 2004, at 22:30 US/Central, Robert G. (Doc) Savage 
wrote:
> Like most hardware devices, you need the right software driver before
> you can use it. I'm far more familiar with Red Hat than with SuSE, but
> check your /var/lib/<kernel_version>/kernel/drivers/scsi directory for
> the driver for your controller. If you can specify that driver during
> installation, your RAID array should appear as a single /dev/sda 
> device.

Out of curiosity, if linux doesn't know the driver, how can I know what 
driver to specify for the controller?

For example, on our Dells use RAID cards and I would have no idea what 
driver should be used for our RAID cards.  Yet, Linux "knows".  lspci 
lists this:

$ sudo lspci -v -s 04:03
04:03.0 RAID bus controller: Dell Computer Corporation PowerEdge 
Expandable RAID Controller 4/Di (rev 02)
         Subsystem: Dell Computer Corporation: Unknown device 014a
         Flags: bus master, stepping, 66Mhz, medium devsel, latency 32, 
IRQ 18
         Memory at f0000000 (32-bit, prefetchable) [size=128M]
         Memory at fcd00000 (32-bit, non-prefetchable) [size=256K]
         Expansion ROM at fcc00000 [disabled] [size=32K]
         Capabilities: [c0] Power Management version 2
         Capabilities: [d0] Message Signalled Interrupts: 64bit+ 
Queue=0/1 Enable-
         Capabilities: [e0] PCI-X non-bridge device.

And the driver reported by dmesg is megaraid:

megaraid: v1.18f (Release Date: Tue Dec 10 09:54:39 EST 2002)
megaraid: found 0x1028:0x000f:idx 0:bus 4:slot 3:func 0
scsi0 : Found a MegaRAID controller at 0xf8838000, IRQ: 18
scsi0 : Enabling 64 bit support
megaraid: [4.10:B111] detected 1 logical drives
megaraid: supports extended CDBs.
megaraid: channel[1] is raid.
megaraid: channel[2] is raid.
scsi0 : LSI Logic MegaRAID 4.10 254 commands 15 targs 5 chans 7 luns
blk: queue c4838018, I/O limit 4095Mb (mask 0xffffffff)
scsi0: scanning virtual channel 0 for logical drives.
   Vendor: MegaRAID  Model: LD 0 RAID0   34G  Rev: 4.10
   Type:   Direct-Access                      ANSI SCSI revision: 02

Fortunately, Linux somehow "knows" that megaraid is the right driver.  
My question is how does it know?

Regards,
- Robert
OpenSource for Windows, Linux, and Mac OS/X
http://www.cwelug.org/downloads


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