[WBEL-users] Adding to RAID 1, only sees new partition as spare... {Scanned} {Scanned}

[Kirby C. Bohling]

On Wed, May 18, 2005 at 02:34:57PM -0700, Scott Silva wrote:
> Kirby C. Bohling wrote:
> > On Wed, May 18, 2005 at 01:06:25PM -0700, Scott Silva wrote:
> > 
> >>Benjamin Smith wrote:
> >>
> >>
> >>>It appears that it's simply not possible to "add" drives to a RAID 1 array. 
> >>>raidreconf does not support RAID 1. 
> >>>
> >>>I had to start from scratch, reinitialize the array with both drives, run 
> >>>mke2fs, and recopy the data back over from the original drive. It took 
> >>>another 17 hours to copy everything, (ugh) but it's all up and working fine 
> >>>now. 
> >>>
> >>>Thanks! 
> >>>
> >>>-Ben 
> >>>
> >>>On Tuesday 17 May 2005 15:15, Scott Silva wrote:
> >>> 
> >>>
> >>>
> >>>>Benjamin Smith wrote:
> >>>>   
> >>>>
> >>>>
> >>>>>I have a server that does backups, and I want to replace an existing 160 
> >>>>>     
> >>>>>
> >>>
> >>>GB 
> >>> 
> >>>
> >>>
> >>>>>drive, with a RAID 1 300 GB array. 
> >>>>>
> >>>>>I don't have enough IDE slots to mount all at the same time. So, I 
> >>>>>     
> >>>>>
> >>>
> >>>installed a 
> >>> 
> >>>
> >>>
> >>>>>single 300 GB HDD, configured it as /dev/md0 RAID 1, made a filesystem, 
> >>>>>mounted, and copied all the data over. It's seen and mounts fine with all 
> >>>>>data present. 
> >>>>>
> >>>>>Now, I've removed the original 160 GB HDD, and put the other new 300 GB in 
> >>>>>it's place. 
> >>>>>
> >>>>>I've tried and tried, and I can't get the 2nd 300 GB drive to sync up to 
> >>>>>     
> >>>>>
> >>>
> >>>the 
> >>> 
> >>>
> >>>
> >>>>>first 300 GB drive. It keeps seeing it as a spare... 
> >>>>>
> >>>>>What am I missing? 
> >>>>>
> >>>>>1st 300 GB partn in array (with data on it) /dev/hdh1 
> >>>>>2nd 300 GB partn in array (seen as spare) /dev/hde1 
> >>>>>     
> >>>>>
> >>>>
> >>>>Did you properly partition the new drive as type fd (linux raid)?
> >>>>
> >>>>Maybe you should use mdadm. I have had better luck with it over raidtools.
> >>>>you would use ;
> >>>>
> >>>>sfdisk -d /dev/hdh |sfdisk /dev/hde
> >>>>
> >>>>to clone the partition data, then
> >>>>
> >>>>mdadm -a /dev/md0 /dev/hde1
> >>>>
> >>>>
> >>>>   
> >>>>
> >>
> >>I know you can create a raid1 array with only one drive and add the
> >>other drive later, because I have done it.
> >>
> > 
> > 
> > That's really nice, show me a command that changes the number of
> > devices in a RAID device.  That is the crux of your problem.
> > 
> > I've read that you can create a RAID device, and tell it there are
> > two devices, and make one that fails immediatly (any old block
> > device will do the job as long as it appears to be large enough).
> > It will write the meta-data to the first block device so it looks
> > like it has two devices.  (Essentially, you are creating a mirror
> > with a device that fails immediatly, and then adding a new device
> > later).
> > 
> > I've never seen anyone actually do it.
> > 
> > 	Thanks,
> > 		Kirby
> 
> mdadm --create /dev/md1 --level=raid1 --raid-devices=2 /dev/sda1 missing
> would create a 2 drive array with only one drive present.
> Later you could add the second drive with mdadm -a /dev/md1 /dev/hdc1 or
> whatever drive you wanted to add.

Good trick (I'll have to remember that one).  For the original
poster, I believe that won't help him at this point, but would have
solved his problem if the original mirror had been setup that way.

    Kirby