mdadm --grow Hard Drive Size Puzzle
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From: Aaron Greenspan <hidden>
Date: 2012-09-30 02:19:34
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
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e-mail aarong@thinkcomputer.com
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