Trouble building a RAID 4 array with mdadm
Kevin O'Gorman
kogorman at gmail.com
Sun Apr 2 04:13:03 UTC 2017
I'm on Xubuntu 16.04.2 LTS, using mdadm. I've already built a RAID-1 array
and had some success with it. I'm trying to build a RAID 5 array, and
having troubles.
I'm using the instructions I found on DigitalOcean (http://goo.gl/ZzwyxQ)
I did the mdadm --create, thus:
mdadm --create --verbose /dev/md3 --level=5 --raid-devices=3 /dev/sdd1
/dev/sde1 /dev/sdf1
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: size set to 3906885632K
mdadm: automatically enabling write-intent bitmap on large array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md3 started.
and /proc/mdstat contained
md3 : active raid5 sdf1[3] sde1[1] sdd1[0]
7813771264 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2]
[UU_]
[>....................] recovery = 0.1% (4734656/3906885632)
finish=1030.1min speed=63128K/sec
bitmap: 0/30 pages [0KB], 65536KB chunk
unused devices: <none>
which indicates that adding the parity should take about 17 hours.
About an hour later it said
md3 : active raid5 sdf1[3] sde1[1] sdd1[0]
7813771264 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2]
[UU_]
[>....................] recovery = 0.8% (33160860/3906885632)
finish=346.9min speed=186077K/sec
bitmap: 0/30 pages [0KB], 65536KB chunk
unused devices: <none>
And I thought that was going awfully fast. Now, less than 3 hours later,
it's saying
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
[raid4] [raid10]
md3 : active raid5 sde1[1] sdd1[0]
7813771264 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2]
[UU_]
bitmap: 2/30 pages [8KB], 65536KB chunk
unused devices: <none>
And you'd think that means the construction is done. But wait a minute.
It only shows 2 drives, and lsblk(8) says /dev/sdf1 is not part of the
array.
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 1.8T 0 disk
├─sda1 8:1 0 1M 0 part
├─sda2 8:2 0 32G 0 part /
├─sda3 8:3 0 32G 0 part
├─sda4 8:4 0 1G 0 part
├─sda5 8:5 0 96G 0 part /vhome
├─sda6 8:6 0 64G 0 part /var/www
├─sda7 8:7 0 32G 0 part /vhome/kevin/VM
├─sda8 8:8 0 190.1G 0 part /vhome/kevin/Projects
├─sda9 8:9 0 2G 0 part [SWAP]
└─sda10 8:10 0 1.4T 0 part
sdb 8:16 0 447.1G 0 disk
├─sdb1 8:17 0 100M 0 part
├─sdb2 8:18 0 446.6G 0 part
└─sdb3 8:19 0 450M 0 part
sdc 8:32 0 3.7T 0 disk
├─sdc1 8:33 0 1M 0 part
├─sdc2 8:34 0 32G 0 part [SWAP]
├─sdc3 8:35 0 64G 0 part
├─sdc4 8:36 0 32G 0 part /vhome/kevin/hex
├─sdc5 8:37 0 32G 0 part /vhome/kevin/hex/build
├─sdc6 8:38 0 192G 0 part
├─sdc7 8:39 0 64G 0 part
├─sdc8 8:40 0 32G 0 part
├─sdc9 8:41 0 32G 0 part
└─sdc10 8:42 0 3.2T 0 part /tmp
sdd 8:48 0 3.7T 0 disk
└─sdd1 8:49 0 3.7T 0 part
└─md3 9:3 0 7.3T 0 raid5
└─md3p1 259:1 0 7.3T 0 md /raid
sde 8:64 0 3.7T 0 disk
└─sde1 8:65 0 3.7T 0 part
└─md3 9:3 0 7.3T 0 raid5
└─md3p1 259:1 0 7.3T 0 md /raid
sdf 8:80 0 3.7T 0 disk
└─sdf1 8:81 0 3.7T 0 part
sdg 8:96 0 1.8T 0 disk
└─sdg1 8:97 0 1.8T 0 part
sr0 11:0 1 1024M 0 rom
Where did I go wrong? What's happening here? Does anybody know?
Why does mdstat show only 2 drives, but is not calling that an error since
it's RAID-5?
--
Kevin O'Gorman
#define QUESTION ((bb) || (!bb)) /* Shakespeare */
Please consider the environment before printing this email.
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