Will #mdadm --create delete data on my partition?

[sunpyo]

I've been through all I can with trying to --assemble my Raid 5 data. However I've heard that #mdadm --create will recreate my RAID intuitively because it recognizes the previously created array parameters and such. So just to get some clarification,

Will mdadm #create delete any of the data on my partitions or will it just recreate the array? Thanks!

[laluz]

how about "man mdadm" ?
"mdadm --assemble --scan" is probably what you are looking for.

[freackout]

I've been through all I can with trying to --assemble my Raid 5 data. However I've heard that #mdadm --create will recreate my RAID intuitively because it recognizes the previously created array parameters and such. So just to get some clarification,

Will mdadm #create delete any of the data on my partitions or will it just recreate the array? Thanks!

i once thought i'd lost data wilst messing around with raid disks and ext3/4 ect anyway simply installed a small hard drive and put 9.04 alternate on it and it found all my raid stuff strait away.

[sunpyo]

i already tried:

#mdadm --assemble --scan

I am able to assemble the raid by doing that, however I am unable to browse to look for the data. I also cannot mount or anything like that. I do however know that the partition is ext3. However I cannot mount by doing:

#mount -t ext3 /dev/md2 /media/disk/shares <--- this is the directory it should be mounted to.

Anyhow like I said. I can assemble the raid, but it does not open to view the files or anything.

[tgrimley]

Looks like I was wrong, --create doesn't necessarily destroy your data. I tried it on my virtual machine and it was okay, but ymmv:


tgrimley@tgrimley-virtual:~$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid6 sdd1[3] sdb1[1] sda1[0] sdc1[2]
41929344 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU]

md1 : active raid1 sdf1[1] sde1[0]
2096384 blocks [2/2] [UU]

unused devices: <none>
tgrimley@tgrimley-virtual:~$ mkdir md0mount
tgrimley@tgrimley-virtual:~$ sudo mount /dev/md0 md0mount/
[sudo] password for tgrimley:
tgrimley@tgrimley-virtual:~$ cd md0mount/
tgrimley@tgrimley-virtual:~/md0mount$ ls
lost+found
tgrimley@tgrimley-virtual:~/md0mount$ sudo chown tgrimley /home/tgrimley/md0mount/
tgrimley@tgrimley-virtual:~/md0mount$ sudo echo "tesssssssssst" >> testfile
tgrimley@tgrimley-virtual:~/md0mount$ cat testfile
tesssssssssst
tgrimley@tgrimley-virtual:~/md0mount$ cd ..
tgrimley@tgrimley-virtual:~$ sudo umount md0mount/
tgrimley@tgrimley-virtual:~$ ls md0mount/
tgrimley@tgrimley-virtual:~$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid6 sdd1[3] sdb1[1] sda1[0] sdc1[2]
41929344 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU]

md1 : active raid1 sdf1[1] sde1[0]
2096384 blocks [2/2] [UU]

unused devices: <none>
tgrimley@tgrimley-virtual:~$ sudo mdadm --stop /dev/md0
mdadm: stopped /dev/md0
tgrimley@tgrimley-virtual:~$ sudo mdadm --create /dev/md0 --level=raid6 --raid-disks=4 /dev/sd[a-d]1
mdadm: /dev/sda1 appears to contain an ext2fs file system
size=41929344K mtime=Wed Sep 16 16:38:45 2009
mdadm: /dev/sda1 appears to be part of a raid array:
level=raid6 devices=4 ctime=Wed Sep 2 18:08:49 2009
mdadm: /dev/sdb1 appears to contain an ext2fs file system
size=41929344K mtime=Wed Sep 16 16:38:45 2009
mdadm: /dev/sdb1 appears to be part of a raid array:
level=raid6 devices=4 ctime=Wed Sep 2 18:08:49 2009
mdadm: /dev/sdc1 appears to be part of a raid array:
level=raid6 devices=4 ctime=Wed Sep 2 18:08:49 2009
mdadm: /dev/sdd1 appears to contain an ext2fs file system
size=41929344K mtime=Wed Sep 16 16:38:45 2009
mdadm: /dev/sdd1 appears to be part of a raid array:
level=raid6 devices=4 ctime=Wed Sep 2 18:08:49 2009
Continue creating array? y
mdadm: array /dev/md0 started.
tgrimley@tgrimley-virtual:~$ sudo mount /dev/md0 md0mount/
tgrimley@tgrimley-virtual:~$ ls md0mount/
lost+found testfile
tgrimley@tgrimley-virtual:~$ cd md0mount/
tgrimley@tgrimley-virtual:~/md0mount$ cat testfile
tesssssssssst