On Thu, Nov 17, 2011 at 1:29 PM, Mark Knecht <markkne...@gmail.com> wrote: > On Thu, Nov 17, 2011 at 9:25 AM, Neil Bothwick <n...@digimed.co.uk> wrote: >> On Thu, 17 Nov 2011 09:01:46 -0800, Mark Knecht wrote: >> >>> I'm pretty sure I've got the command set right to do the RAID-1 to >>> RAID-5 conversion, but once it's done I believe the file system itself >>> will still be 250GB so I'll need to resize the file system. In the >>> past I've done this with gparted, which seems to work fine, but this >>> time I was considering doing it at the command line. Does anyone know >>> of a good web site that goes through how to do that? I've browsed >>> around and found different pages that talk about it but my reading >>> looks like they all have minor differences which leaves me a bit >>> worried. >> >> Using cfdisk or fdisk, delete the partition and recreate it, USING THE >> SAME START BLOCK at a larger size. >> >> Then "resize2fs /dev/sdwhatever" will resize the filesystem to fill the >> partition. >> >> >> >> -- >> Neil Bothwick > > Really? Delete the partition? Sounds scary! (But actually makes sense. > The data is still there.) > > I'm not sure how this works in the case of a RAID though. Here's the > current partition table for sda where sda6, sdb6 & sdc6 are part of > the RAID-1:: > > c2stable ~ # fdisk -l /dev/sda > > Disk /dev/sda: 500.1 GB, 500107862016 bytes > 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors > Units = sectors of 1 * 512 = 512 bytes > Sector size (logical/physical): 512 bytes / 512 bytes > I/O size (minimum/optimal): 512 bytes / 512 bytes > Disk identifier: 0x8b45be24 > > Device Boot Start End Blocks Id System > /dev/sda1 * 63 112454 56196 83 Linux > /dev/sda2 112455 8514449 4200997+ 82 Linux swap / Solaris > /dev/sda3 8594775 113467094 52436160 fd Linux raid autodetect > /dev/sda4 113467095 976768064 431650485 5 Extended > /dev/sda5 113467158 218339414 52436128+ fd Linux raid autodetect > /dev/sda6 481933935 976768064 247417065 83 Linux > /dev/sda7 218339478 481933871 131797197 fd Linux raid autodetect > > Partition table entries are not in disk order > c2stable ~ # > > It's not that I want to change the partition size of the 3 pieces of > the RAID-1, it's that after I convert the RAID-1 to RAID-5 I want it > to be 500GB. > > > I asked some questions on the Linux RAID list and putting together > info from a couple of people here's how I'm thinking I proceed with > the conversion: > > 1) First, fail one disk and clean it up for later: > > umount /dev/md6 > mdadm --stop /dev/md6 > mdadm /dev/md6 --fail /dev/sdc6 --remove /dev/sdc6 > mdadm --zero-superblock /dev/sdc6 > > At this point the RAID-1 is still 3-drives but one is marked 'failed'. > The failed drive is at this point like a new drive as it has no > superblock. (I think...) > > 2) Now I convert the 3-drive RAID1 to a 2-drive RAID-1: > > mdadm --grow /dev/md6 --raid-devices=2 > > 3) Create a 2-drive RAID-5: > > mdadm has an 'instantaneous' conversion of RAID-1 to RAID-5 for the > 2-drive case because parity of a single drive is just the data itself. > /dev/sdb6 is now 'parity' instead of 'data'. > > mdadm /dev/md6 --grow --level=5 > > 4) Add a 3rd drive to the RAID-5: > > mdadm /dev/md6 --add /dev/sdc6 > mdadm /dev/md6 --grow --raid-devices=3 > > > > At this point I was told: > > "Now, resize your filesystem to use the additional space." > > So, if at this point the end-block of sda6 isn't 976768064 but, let's > say, 700000000 because mdadm set it to something new, then using your > suggestion I guess I'd set it back to 976768064? I'm not comfortable > however that if I do that that whatever is out there beyond 700000000 > is really formatted as ext3 and 'empty' as I don't know what the mdadm > conversion has done to it.
Your resize would be applied not to /dev/sd?, but to /dev/md?. You don't need to worry about what that means on /dev/sd*; the filesystem you want to poke is on /dev/md*. file -s /dev/sd* /dev/md* -- :wq
