[plug] Good RAID Howto

[Kai Jones]

Yes I understand how ide devices work on Linux and thinking about it a 
bit more it figures that sda 1-3 are logical partitions because we have 
mounts for /, /boot and /home

Other than the already listed sda# devies there are no devies (eg sdb, 
sdc, etc) listed in dmesg although with messages like this I'd say we do 
have a hardware RAID controller !

megaraid: v1.15hp (Release Date: Mon Jun 25 11:28:26 EDT 2001)
PCI: Assigned IRQ 9 for device 00:02.0
megaraid: found 0x101e:0x1960:idx 0:bus 0:slot 2:func 0
scsi0 : Found a MegaRAID controller at 0xf8824000, IRQ: 9
megaraid: [H01.08:G01.07] detected 1 logical drives

Pity those messages aren't timestamped....
Anyway, the next change I get I'll reboot the machine and have a look at 
the RAID BIOS to see if anything needs modifying.

Cheers
Kai

Shannon Carver wrote:
> Yea, Ben's right.  I'm not sure if you're familiar with IDE devices 
> under linux but they're always hda/hdb (first channel, master/slave, two 
> devices), hdc/hdd, etc etc).
> 
> So all devices listed as sda, are in fact the one drive, or logical 
> drive (in your case, sda would be the initial RAID array.
> 
> Are there any sd* listed devices in dmesg?
> 
> Regards
> 
> Shannon
> 
> Ben Jensz wrote:
> 
>> Unless you're already running hardware RAID on the current drives in 
>> the system, then sda will be a single physical drive, and sda1, sda2 
>> etc are partitions within that physical drive.
>>
>> If you're running proper hardware RAID, then the drives in whatever 
>> RAID level they are in will appear as one physical drive (i.e. sda 
>> could be multiple drives, but one drive is presented to the OS as it's 
>> been made into a single RAID drive).  But the additional drives you've 
>> added in this case aren't sda5-7.
>>
>> They will be something like sdb, sdc, sdd etc.
>>
>>
>> / Ben
>>
>>
>> Kai Jones wrote:
>>
>>> Running "dmesg | grep sd" gives the following:
>>>
>>> Attached scsi disk sda at scsi0, channel 1, id 0, lun 0
>>> SCSI device sda: 71127040 512-byte hdwr sectors (36417 MB)
>>>  sda: sda1 sda2 < sda5 sda6 sda7 >
>>>
>>> I'm guessing this means sda, sda1 and sda2 are the active RAID1 and 
>>> sda5, 6 and 7 are spares because it doesn't yet know the 3 x 73 gig 
>>> disks are plugged in and waiting ?
>>>
>>> Cheers
>>> Kai