> -----Original Message----- > From: linux-raid-owner@vger.kernel.org > [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Cress, Andrew R > Sent: Wednesday, January 07, 2004 9:48 AM > To: Catalin BOIE; Mircea Ciocan > Cc: linux-raid@vger.kernel.org > Subject: RE: Please help with a special RAID 1 setup > > > Note that RAID-1 will only ever have a maximum of 2 active disks. I don't believe that the above is a correct statement. Linux software RAID1 will allow mirroring across more than 2 devices: [root@cinshrlnxlap01 ~]# cat /proc/mdstat Personalities : [raid1] read_ahead 1024 sectors md2 : active raid1 [dev 01:02][2] [dev 01:01][1] [dev 01:00][0] 4032 blocks [3/3] [UUU] unused devices: <none> [root@cinshrlnxlap01 ~]# mount /dev/md2 /mnt/cdrom/ [root@cinshrlnxlap01 ~]# cd /mnt/cdrom/ [root@cinshrlnxlap01 /mnt/cdrom]# dir total 17 drwxr-xr-x 3 root root 1024 Jan 7 12:09 . drwxr-xr-x 4 root root 4096 Dec 30 07:46 .. drwx------ 2 root root 12288 Jan 7 12:09 lost+found [root@cinshrlnxlap01 /mnt/cdrom]# touch hithere [root@cinshrlnxlap01 /mnt]# umount cdrom/ [root@cinshrlnxlap01 /mnt]# raidstop /dev/md2 [root@cinshrlnxlap01 /mnt]# mount /dev/ram0 /mnt/cdrom/ [root@cinshrlnxlap01 /mnt]# ls -la cdrom/ total 17 drwxr-xr-x 3 root root 1024 Jan 7 12:10 . drwxr-xr-x 4 root root 4096 Dec 30 07:46 .. -rw-r--r-- 1 root root 0 Jan 7 12:10 hithere drwx------ 2 root root 12288 Jan 7 12:09 lost+found [root@cinshrlnxlap01 /mnt]# umount cdrom/ umount: /mnt/cdrom: device is busy [root@cinshrlnxlap01 /mnt]# umount cdrom/ [root@cinshrlnxlap01 /mnt]# mount /dev/ram1 /mnt/cdrom/ [root@cinshrlnxlap01 /mnt]# ls -la cdrom/ total 17 drwxr-xr-x 3 root root 1024 Jan 7 12:10 . drwxr-xr-x 4 root root 4096 Dec 30 07:46 .. -rw-r--r-- 1 root root 0 Jan 7 12:10 hithere drwx------ 2 root root 12288 Jan 7 12:09 lost+found [root@cinshrlnxlap01 /mnt]# umount cdrom/ [root@cinshrlnxlap01 /mnt]# mount /dev/ram2 /mnt/cdrom/ [root@cinshrlnxlap01 /mnt]# ls -la /mnt/cdrom/ total 17 drwxr-xr-x 3 root root 1024 Jan 7 12:10 . drwxr-xr-x 4 root root 4096 Dec 30 07:46 .. -rw-r--r-- 1 root root 0 Jan 7 12:10 hithere drwx------ 2 root root 12288 Jan 7 12:09 lost+found We had a "triple" mirror sofware RAID setup on a box as a "poor man's snapshot" before we started using LVM. We triple mirrored and then broke one mirror to backup and then added the removed disk back into the array and re-synched. LVM snapshots are much more elegant and LVM provides more functionality such as extended volumes when you want to add more space. You have to be careful using LVM because as of 2.4.18 there was a Linux VM bug that would not allow snapshotting with greater than about 6GB of system RAM. However, I would recommend recreating the filesystem on top of LVM and using snapshots to accomplish what you want. We use LVM on top of SW RAID with great success. > When you add the 3rd disk, it is added to the array as a > spare, that's why it doesn't rebuild. > > Andy > > -----Original Message----- > From: linux-raid-owner@vger.kernel.org > [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Catalin BOIE > Sent: Wednesday, January 07, 2004 8:48 AM > To: Mircea Ciocan > Cc: linux-raid@vger.kernel.org > Subject: Re: Please help with a special RAID 1 setup > > > > >I think that you must replace: > > > nr-raid-disks 2 > > >with > > > nr-raid-disks 3 > > >Plus, the correspinding entry: > > > device /dev/sdb3 > > > raid-disk 2 > > > > > >Else, the third drive isn't recognized as part of the md array. > > >Probably, you must restart the array (only first time). > > >You may want to use mdadm instead of raidtools. > > > > > > > > > > > > > Modified config file, umounted and stoped raid, restarted raid, > > hotadded the disk, still the same results :(. > > Any other ideeas ?? > > > > Mircea > > I think you must rebuid the /dec/md0 with mkraid --upgrade. > Warning! You may destroy all data, so backup first. > > --- > Catalin(ux) BOIE > catab@deuroconsult.ro > - > To unsubscribe from this list: send the line "unsubscribe > linux-raid" in the body of a message to > majordomo@vger.kernel.org More majordomo info at > http://vger.kernel.org/majordomo-info.html > - > To unsubscribe from this list: send the line "unsubscribe > linux-raid" in the body of a message to > majordomo@vger.kernel.org More majordomo info at > http://vger.kernel.org/majordomo-info.html > > - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
