lkml.org 
[lkml]   [2002]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: RAID superblock confusion
    On Saturday April 13, rgooch@ras.ucalgary.ca wrote:
    > Neil Brown writes:
    > > On Wednesday April 10, rgooch@ras.ucalgary.ca wrote:
    > > >
    > > > The device is set up (i.e. SCSI host driver is loaded) long before I
    > > > do raidstart /dev/md/0
    > >
    > > raidstart simply does not and cannot work reliably when your device
    > > numbers change around. It takes the first device listed in
    > > /etc/raidtab and gives it to the kernel.
    > > The kernel reads the superblock, finds some device numbers and tries
    > > to attach those devices. If device number have changed, you loose.
    >
    > Sounds to me like the flaw is in the ioctl(2) interface, in that it
    > doesn't allow passing all the block devices in the RAID set. If it
    > allowed you to pass all the block devices, then it could check if all
    > the signatures on each block device match.

    Exactly. The flaw is in the ioctl interface. 2.4 comes with an
    improved ioctl interface which allows you to tell the kernel exactly
    what you want it to do. mdadm used this interface.

    >
    > I tried the alternative of setting persistent-superblock=0 in
    > /etc/raidtab, but the stupid thing complained because it found a
    > superblock. Sigh.
    >
    > If there was only a "do as I say, regardless" mode, I would be happy.
    > This programmer-knows-best attitude smacks of M$.

    mdadm will do as you say, reguardless - if you ask it to. Have you
    tried mdadm?
    http://www.cse.unsw.edu.au/~neilb/source/mdadm/

    NeilBrown
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:25    [W:0.031 / U:0.368 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site