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. > 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. > > > What is unclear to me is where the system mounts the filesystems > on /dev/mapper/silXXXXXX and how the dm-mirror module manages drive > failues. Can someone fill in the pieces for me? /etc/fstab is filled during installation. A failed drive is being ignored by dm-mirror until you replace it using the ATARAID bios (sil in your case). Online replacement for dmraid/device-mapper is still in the works. Regards, Heinz > > Sean > > _______________________________________________ > Ataraid-list mailing list > Ataraid-list@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/ataraid-list =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat GmbH Consulting Development Engineer Am Sonnenhang 11 Storage Development 56242 Marienrachdorf Germany Mauelshagen@xxxxxxxxxx PHONE +49 171 7803392 FAX +49 2626 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _______________________________________________ Ataraid-list mailing list Ataraid-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ataraid-list
