From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco De Vitis Subject: mdadm and size differences Date: Tue, 24 Nov 2015 11:32:33 +0100 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi, I cannot understand a difference in size I can see on an old Debian 5.0 machine, maybe I'm just missing something obvious. /dev/sdd is partitioned as follows, and /dev/sdf is exactly the same: > #>fdisk -l /dev/sdd > > Disk /dev/sdd: 500.1 GB, 500107862016 bytes > 255 heads, 63 sectors/track, 60801 cylinders > Units = cylinders of 16065 * 512 = 8225280 bytes > Disk identifier: 0x000901d8 > > Device Boot Start End Blocks Id System > /dev/sdd1 1 24 192748+ 83 Linux > /dev/sdd2 25 60801 488191252+ 5 Extended > /dev/sdd5 25 632 4883728+ 83 Linux > /dev/sdd6 633 2982 18876343+ 83 Linux > /dev/sdd7 2983 4199 9775521 83 Linux > /dev/sdd8 4200 4807 4883728+ 83 Linux > /dev/sdd9 4808 5173 2939863+ 82 Linux swap / Solaris > /dev/sdd10 5174 31281 209712478+ 83 Linux You can see that sdd6 is twice the size of sdd7. cfdisk reports sizes of around 20 GB and 10 GB: sdd6 -> 19329.41 sdd7 -> 10010.17 All partitions in these two identical drives are configured as RAID 1 using mdadm, but the md devices associated to sdd6/sdf6 and sdd7/sdf7 are both reported to be 10 GB in size, as can be seen from the mdadm output below. Why? Thanks for any info. > #>mdadm -vv --detail /dev/md2 > /dev/md2: > Version : 00.90 > Creation Time : Thu Feb 22 16:18:11 2007 > Raid Level : raid1 > Array Size : 9767424 (9.31 GiB 10.00 GB) > Used Dev Size : 9767424 (9.31 GiB 10.00 GB) > Raid Devices : 2 > Total Devices : 2 > Preferred Minor : 2 > Persistence : Superblock is persistent > > Update Time : Mon Nov 23 14:19:23 2015 > State : clean > Active Devices : 2 > Working Devices : 2 > Failed Devices : 0 > Spare Devices : 0 > > UUID : 5582dad7:7ac89883:0c2b9e1d:5009dd35 > Events : 0.69228 > > Number Major Minor RaidDevice State > 0 8 54 0 active sync /dev/sdd6 > 1 8 86 1 active sync /dev/sdf6 > > #>mdadm -vv --detail /dev/md3 > /dev/md3: > Version : 00.90 > Creation Time : Thu Feb 22 16:18:54 2007 > Raid Level : raid1 > Array Size : 9767424 (9.31 GiB 10.00 GB) > Used Dev Size : 9767424 (9.31 GiB 10.00 GB) > Raid Devices : 2 > Total Devices : 2 > Preferred Minor : 3 > Persistence : Superblock is persistent > > Update Time : Mon Nov 23 14:19:27 2015 > State : clean > Active Devices : 2 > Working Devices : 2 > Failed Devices : 0 > Spare Devices : 0 > > UUID : e44836cf:6340f7fa:52fb3562:a78d4dbb > Events : 0.187630 > > Number Major Minor RaidDevice State > 0 8 55 0 active sync /dev/sdd7 > 1 8 87 1 active sync /dev/sdf7 -- Ciao, Marco.