Hi Neil, I found your personal web site by doing a Google search on mdadm, so I'm not sure if you are the right person to ask this of, or if it's a dumb question in the first place, but here's what I'm running into. I had a RAID 1 array on CentOS 6 (which comes with mdadm 3.2.3) of two 250GB SATA Western Digital hard drives. It was finally time to upgrade their capacity, so I purchased two 2TB SATA Seagate hard drives. I replaced them one at a time, first by removing old drive B (slot 1), then copying over the partitions from old drive A (slot 0) to new drive C (slot 1), and then swapping the drives so that I could copy the partitions from new drive C (slot 0) to drive D (slot 1). This generally worked fine, with one exception. As I said, the drives are 2TB each. Somehow I'm only being given 1TB to work with. Here's what mdadm reports for the first new drive: [root@kermit plainsite]# mdadm --examine /dev/sda5 /dev/sda5: Magic : a92b4efc Version : 1.1 Feature Map : 0x0 Array UUID : 15f9c88e:502e7c20:cdceb61e:fa745c07 Name : localhost.localdomain:3 Creation Time : Tue Aug 9 13:31:58 2011 Raid Level : raid1 Raid Devices : 2 Avail Dev Size : 3462374884 (1650.99 GiB 1772.74 GB) Array Size : 1731187442 (825.49 GiB 886.37 GB) Used Dev Size : 1731187442 (825.49 GiB 886.37 GB) Data Offset : 2048 sectors Super Offset : 0 sectors State : clean Device UUID : bbe2518d:ccd383d3:476b9ab4:54f4f1f7 Update Time : Sat Sep 29 20:09:12 2012 Checksum : 725e9e7d - correct Events : 16261 Device Role : Active device 1 Array State : AA ('A' == active, '.' == missing) ...and the second... [root@kermit plainsite]# mdadm --examine /dev/sdb5 /dev/sdb5: Magic : a92b4efc Version : 1.1 Feature Map : 0x0 Array UUID : 15f9c88e:502e7c20:cdceb61e:fa745c07 Name : localhost.localdomain:3 Creation Time : Tue Aug 9 13:31:58 2011 Raid Level : raid1 Raid Devices : 2 Avail Dev Size : 3462374884 (1650.99 GiB 1772.74 GB) Array Size : 1731187442 (825.49 GiB 886.37 GB) Used Dev Size : 1731187442 (825.49 GiB 886.37 GB) Data Offset : 2048 sectors Super Offset : 0 sectors State : clean Device UUID : dd133b6e:55cf2958:4b39275f:4f9d2cf3 Update Time : Sat Sep 29 20:09:12 2012 Checksum : 7db54225 - correct Events : 16261 Device Role : Active device 0 Array State : AA ('A' == active, '.' == missing) The big question is why the "Avail Dev Size" is 1772.74 GB, but the "Array Size" is only 886.37 GB. When I run mdadm --grow /dev/md3 --size=max, I get this: [root@kermit plainsite]# mdadm --grow /dev/md3 --size=max mdadm: component size of /dev/md3 unchanged at 865593721K If I try to force it, I get this: [root@kermit plainsite]# mdadm --grow /dev/md3 --size=1731187442 mdadm: Cannot set device size for /dev/md3: No space left on device The other partitions are not taking up the other 1TB; it definitely seems available. Just so you have more data, here's the output of some other commands: --- [root@kermit plainsite]# more /proc/mdstat Personalities : [raid1] md2 : active raid1 sdb3[3] sda3[2] 1020115 blocks super 1.2 [2/2] [UU] md3 : active raid1 sdb5[2] sda5[3] 865593721 blocks super 1.1 [2/2] [UU] md1 : active raid1 sdb2[2] sda2[3] 221182844 blocks super 1.1 [2/2] [UU] bitmap: 0/2 pages [0KB], 65536KB chunk md0 : active raid1 sdb1[2] sda1[3] 102388 blocks super 1.0 [2/2] [UU] unused devices: <none> --- [root@kermit etc]# hdparm -i /dev/sda /dev/sda: Model=ST2000DM001-9YN164, FwRev=CC46, SerialNo=W2F02P7Y Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=3907029168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=yes: unknown setting WriteCache=enabled Drive conforms to: unknown: ATA/ATAPI-4,5,6,7 * signifies the current active mode --- [root@kermit etc]# hdparm -i /dev/sdb /dev/sdb: Model=ST2000DM001-9YN164, FwRev=CC46, SerialNo=W2F02PE2 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=3907029168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=yes: unknown setting WriteCache=enabled Drive conforms to: unknown: ATA/ATAPI-4,5,6,7 * signifies the current active mode --- [root@kermit /]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/md3 852011868 730683448 78060472 91% / tmpfs 2010380 0 2010380 0% /dev/shm /dev/md0 99138 90797 3222 97% /boot /dev/md1 217711416 104934568 101717708 51% /home --- [root@kermit etc]# more mdadm.conf # mdadm.conf written out by anaconda MAILADDR root AUTO +imsm +1.x -all ARRAY /dev/md0 level=raid1 num-devices=2 UUID=1871a7f9:dcb6f1e0:53fc2afe:edc5ea24 ARRAY /dev/md1 level=raid1 num-devices=2 UUID=96b2d1ae:401c7fd8:da33bdac:4a5c1252 ARRAY /dev/md2 level=raid1 num-devices=2 UUID=6f6eecca:718bd092:ddf96dca:18317b4c ARRAY /dev/md3 level=raid1 num-devices=2 UUID=15f9c88e:502e7c20:cdceb61e:fa745c07 --- [root@kermit etc]# mdadm --detail /dev/md3 /dev/md3: Version : 1.1 Creation Time : Tue Aug 9 13:31:58 2011 Raid Level : raid1 Array Size : 865593721 (825.49 GiB 886.37 GB) Used Dev Size : 865593721 (825.49 GiB 886.37 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Sat Sep 29 17:49:37 2012 State : active Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Name : localhost.localdomain:3 UUID : 15f9c88e:502e7c20:cdceb61e:fa745c07 Events : 15287 Number Major Minor RaidDevice State 2 8 21 0 active sync /dev/sdb5 3 8 5 1 active sync /dev/sda5 --- Any thoughts? Thanks, Aaron Aaron Greenspan President & CEO Think Computer Corporation telephone +1 415 670 9350 toll free +1 888 815 8599 fax +1 415 373 3959 e-mail aarong@xxxxxxxxxxxxxxxxx web http://www.thinkcomputer.com-- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html