On Mon, 2007-10-22 at 12:16 +0200, Heinz Mauelshagen wrote: > On Thu, Oct 11, 2007 at 10:57:39AM -0700, Sean Bruno wrote: > > I am trying to delve into dmraid/device-mapper and learn how the magic > > happens and I came up with what I think is the "way it works." Please > > critique and correct me where I am wrong or over-simplify the operation > > of the current dmraid architecture as it is used under Fedora/redhat > > systems. > > > > Assumptions: > > dmraid compatible device(sil3118) > > Hard Drives of equal size(SATA in my case) > > Installation of Fedora Core 7(x86_64) > > > > 1. > > The initial setup occurs on the RAID controller where I selected RAID1 > > with my two disks. This initialized the drives for use with > > dmraid/device-mapper by placing the SiL metadata on the drives and set > > them to a initialized state. > > Well, it just puts vendor specific metedata on the drives making up > a RAID set. Vendors typically ship M$ drivers and a managent tool to use > such ATARAID sets on Windows. > > > > > 2. > > The system boots off the first hard drive(sda) and loads the kernel from > > there. > > As part of the initrd actions, a mirrored mapping gets activated for > your RAID1 set. > > > > > 3. > > Booting Fedora Core 7, /etc/rc.sysinit loads the fake RAID1 module > > "dm-mirror". This actually works with the software RAID code in md to > > manage the RAID1. > > No need for MD. dm-mirror is a selve-contained device-mapper mirroring > implementation. > I thought(from reading the code), that dm-mirror is a module that uses MD functions(it's built on top of the s/w raid code). > > The system then detects that the drives are a RAID1 > > set by invoking '/sbin/dmraid -ay -i -p -t' This detects the RAID1 set > > and creates /dev/mapper/silXXXXXXX through the device-mapper libraries. > > Like I said, activation happens in the initrd. > Specifically, I was looking at the redhat startup script /etc/rc.sysinit. Is this how the system figures out that there's a RAID device to deal with? Sean _______________________________________________ Ataraid-list mailing list Ataraid-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ataraid-list
