aic79xx and RAID ?
Hi,
I have a question about the aic79xx driver and RAID.
A friend of mine tries to install Linux on a IBM rack server machine, which has two hard disks and a aic 7902 SCSI/RAID controller. He has configured both disks as a RAID1 mirror in the BIOS.
However, when booting Linux (SuSE or Knoppix), the kernel recognizes the controller and loads the aic79xx driver, but does not recognize the RAID mirror. Instead it presents both disks as separate disks /dev/sda and /dev/sdb.
I could not find any documentation except that which comes with the kernel (Documentation/scsi/aic79xx.txt), but it doesn't say anything about RAID.
Where could I find any hint about how to use RAID disks with aic7902 cards?
regards
Hadmut Danisch
Quoted 6 lines · Hadmut Danisch
Hi,
I have a question about the aic79xx driver and RAID.
A friend of mine tries to install Linux on a IBM rack server machine, which has two hard disks and a aic 7902 SCSI/RAID controller.
ah one of the software raid controllers
Quoted 4 lines
However, when booting Linux (SuSE or Knoppix), the kernel recognizes the controller and loads the aic79xx driver, but does not recognize the RAID mirror. Instead it presents both disks as separate disks
/dev/sdaand/dev/sdb.
this is in principle the right thing for this kind of software raid. the dmraid tool is there to support this type of software raid (bios supported raid) but I don't think it supports adaptec raid yet...
Hi,
thanks for the fast reply. :-)
Quoted 3 lines · Arjan van de Ven
ah one of the software raid controllers
..
Quoted 3 lines
this is in principle the right thing for this kind of software raid. the dmraid tool is there to support this type of software raid (bios supported raid) but I don't think it supports adaptec raid yet...
A software raid controller? Never heard of such a beast before.
I always thought that there are exactly two ways to do raid, one way is to have it all hidden in the controller, which makes the RAID mirror appear as just a single disk to the kernel, and the other way is to use the kernel software raid (configured with mdadm).
I've never heard of a software raid controller, where the kernel must do the work itself. After all, what's the controller's job and why is it called a RAID controller then?
But I guess we have to use software (i.e. kernel driven, mdadm) raid then?
regards
Hadmut
Quoted 9 lines
..
Quoted 3 lines
this is in principle the right thing for this kind of software raid. the dmraid tool is there to support this type of software raid (bios supported raid) but I don't think it supports adaptec raid yet...
A software raid controller? Never heard of such a beast before.
it's software raid but with support from the cards bios so that you can boot from it.
Quoted 4 lines
I always thought that there are exactly two ways to do raid, one way is to have it all hidden in the controller, which makes the RAID mirror appear as just a single disk to the kernel, and the other way is to use the kernel software raid
this is basically a correct understanding, and your card is of the second type.
Quoted 2 lines
(configured with
mdadm).
there are multiple classes of software raid now; some are driven by device mapper.
Quoted 3 lines
I've never heard of a software raid controller, where the kernel must do the work itself. After all, what's the controller's job and why is it called a RAID controller then?
marketing speak... the kernel does all the work. just they sell you a driver for windows that hides this, as well as a bios rom that allows you to boot from it.... but other than that it's just software raid.
Quoted 3 lines
But I guess we have to use software (i.e. kernel driven, mdadm) raid then?
as I said, dmraid (using device mapper) is designed for this type of software raid...
Quoted 10 lines · Hadmut Danisch
A software raid controller? Never heard of such a beast before.
I always thought that there are exactly two ways to do raid, one way is to have it all hidden in the controller, which makes the RAID mirror appear as just a single disk to the kernel, and the other way is to use the kernel software raid (configured with mdadm).
I've never heard of a software raid controller, where the kernel must do the work itself. After all, what's the controller's job and why is it called a RAID controller then?
Marketing.
Read http://linux.yyz.us/sata/faq-sata-raid.html
Jeff
Quoted 11 lines · Jeff Garzik
Quoted 9 lines · Hadmut Danisch
A software raid controller? Never heard of such a beast before. I always thought that there are exactly two ways to do raid, one way is to have it all hidden in the controller, which makes the RAID mirror appear as just a single disk to the kernel, and the other way is to use the kernel software raid (configured with mdadm). I've never heard of a software raid controller, where the kernel must
do the work itself. After all, what's the controller's job and why is it called a RAID controller then?
Quoted 3 lines
Marketing.
Well... your site doesn't list this "HostRAID" euphemism for software RAID on SCSI ;-)
Seriously, could you add ICH7-R to your fakeraid list, too? It appears to be software RAID, too.
And perhaps a link to <http://linuxmafia.com/faq/Hardware/sata.html>.
Signature · 1 line
Matthias Andree