I've been trying to resize (--grow) this RAID array for a week and I know the answer is simple and probably staring me in the face, but I'm not sleep deprived and lost.
The array is RAID1 and used to consist of two 2TB hard drives and was not configured by me. The client ran out of space and I replaced the drives with two 4TB drives. I copied over the partition tables with sgdisk or something like that, but later removed some partitions and made the one in question bigger.
I've removed one of the drives on purpose so I don't mess up both of them. You may see references to it here and there, it's as expected
TL;DR
--grow --size=max doesn't work, gives unchanged at 3896741888K
--update=devicesize shows larger size, but --grow still doesn't work
sda and sdb are identical and look like this sd{a,b}3 is the partition in question
Disk /dev/sda: 3.7 TiB, 4000787030016 bytes, 7814037168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 4230A82E-F626-4A32-B4FD-F0A91A30F64C
Device Start End Sectors Size Type
/dev/sda1 2048 3905535 3903488 1.9G Linux RAID
/dev/sda2 3905536 3907583 2048 1M BIOS boot
/dev/sda3 3907584 7797653503 7793745920 3.6T Linux RAID
/dev/sda7 7797653504 7814037134 16383631 7.8G Linux RAID
As you can see, 3.6TB or so. Looking good so far.
Lets look at the partition itself, again both drives look the same
mdadm --examine /dev/sda3
/dev/sda3:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 49d82293:715e6baf:3f0a3f79:b2089367
Name : c4root:1
Creation Time : Wed Apr 2 20:56:22 2014
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 7793483776 (3716.22 GiB 3990.26 GB) #yay (hopes going up)
Array Size : 3896741888 (3716.22 GiB 3990.26 GB) #oldsize (as expected)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262056 sectors, after=0 sectors
State : clean
Device UUID : 3aa675c5:761465e5:886a395d:95eac69d
Update Time : Mon Oct 25 04:35:56 2021
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 68eed7f7 - correct
Events : 1021990
Device Role : Active device 0
Array State : A. ('A' == active, '.' == missing, 'R' == replacing)
Looking good again. We've got the Avail Dev Size looking good, the Array size is where it's currently at. Lets move on to the array info
mdadm --details /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Wed Apr 2 20:56:22 2014
Raid Level : raid1
Array Size : 3896741888 (3716.22 GiB 3990.26 GB)
Used Dev Size : 3896741888 (3716.22 GiB 3990.26 GB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Update Time : Mon Oct 25 04:35:56 2021
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Name : c4root:1
UUID : 49d82293:715e6baf:3f0a3f79:b2089367
Events : 1021990
Number Major Minor RaidDevice State
2 8 3 0 active sync /dev/sda3
2 0 0 2 removed
That array size is still showing the old size.
I read online that you may need to do an update on the device size as you assemble it. Lets do that.
# mdadm -S /dev/md1
mdadm: stopped /dev/md1
# mdadm --assemble --update=devicesize /dev/md1
Size was 7793483776
Size is 7793483776
mdadm: /dev/md1 has been started with 1 drive (out of 2).
Okay, looks like it knows it has room to grow. Lets try to grow it!
# mdadm --grow --size=max /dev/md1
mdadm: component size of /dev/md1 unchanged at 3896741888K
and the -D details STILL show the old size...
/dev/md1:
Version : 1.2
Creation Time : Wed Apr 2 20:56:22 2014
Raid Level : raid1
Array Size : 3896741888 (3716.22 GiB 3990.26 GB)
Used Dev Size : 3896741888 (3716.22 GiB 3990.26 GB)
Raid Devices : 2
Total Devices : 1
What in the world am I missing?
