Hello,
is it possible to create md partitions larger than 0.4TB?
We have >=9TB RAID-0 systems, and I tried to create a partitionable
two-partition md with mdadm --auto=mdp2 and partition it into for example
16MB and ~9TB. For partitioning /dev/md_d0 I have tried sfdisk, fdisk,
cfdisk, parted, ... Regardless of the partitioning tool, the ~9TB
partition always ends up as 455780.07MB i.e. 0.4TB.
There is no problem to create a large 9TB single partition on a
non-partitionable /dev/md0. Is the 445097720 blocks (0.4TB) "cropping" a
bug or a real limitation with mdp partitionable raid?
Further infos below.
root@abidal:~# uname -a
Linux abidal 2.6.27-7-generic #1 SMP Tue Nov 4 19:33:06 UTC 2008 x86_64 GNU/Linux
root@abidal:~# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.10
DISTRIB_CODENAME=intrepid
DISTRIB_DESCRIPTION="Ubuntu 8.10"
root@abidal:~# cat /proc/partitions|grep md
254 0 9035047936 md_d0
254 1 15622 md_d0p1
254 2 445097720 md_d0p2
root@abidal:~# sfdisk /dev/md_d0
Checking that no-one is using this disk right now ...
OK
Disk /dev/md_d0: 2258761984 cylinders, 2 heads, 4 sectors/track
Old situation:
Units = cylinders of 4096 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/md_d0p1 0+ 3905 3906- 15622 83 Linux
/dev/md_d0p2 3906 111278335 111274430 445097720 83 Linux
/dev/md_d0p3 0 - 0 0 0 Empty
/dev/md_d0p4 0 - 0 0 0 Empty
root@abidal:~# mdadm -D /dev/md0
mdadm: md device /dev/md0 does not appear to be active.
root@abidal:~# mdadm -D /dev/md_d0
/dev/md_d0:
Version : 00.90
Creation Time : Thu Nov 13 11:58:59 2008
Raid Level : raid0
Array Size : 9035047936 (8616.49 GiB 9251.89 GB)
Raid Devices : 12
Total Devices : 12
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Thu Nov 13 11:58:59 2008
State : clean
Active Devices : 12
Working Devices : 12
Failed Devices : 0
Spare Devices : 0
Chunk Size : 1024K
UUID : f1945a73:83d2bea9:b96e9208:11a3b9ec (local to host
abidal)
Events : 0.1
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
4 8 81 4 active sync /dev/sdf1
5 8 97 5 active sync /dev/sdg1
6 8 113 6 active sync /dev/sdh1
7 8 129 7 active sync /dev/sdi1
8 8 145 8 active sync /dev/sdj1
9 8 161 9 active sync /dev/sdk1
10 8 177 10 active sync /dev/sdl1
11 8 193 11 active sync /dev/sdm1
thanks,
- Jan
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