A linux utility used to manage software RAID devices.

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6
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2answers
2k views

Will the system make sure that mdadm is sync-ed before completing a reboot?

This is a follow up to my crazy mdadm problem. I'm trying to figure out what might have caused sda to get out of sync in the first place. The only thing I can think of is that I had just run a bunch ...
5
votes
3answers
3k views

How to safely replace a not-yet-failed disk in a Linux RAID5 array?

I have a software RAID5 array (Linux md) on 4 disks. I would like to replace one of the disks with a new one, without putting the array in a degraded state, and if possible, online. How would that ...
1
vote
1answer
70 views

Unable to check a mdadm RAID1 array, says the file system's read only?

I recently migrated a RAID1 from a CentOS 5 system to a CentOS 6 system and ever since when I attempt to perform a check I get the following: $ echo 'check' > /sys/block/md127/md/sync_action ...
15
votes
3answers
4k views

Difference between UUID from blkid and mdadm?

Can someone explain the difference between the UUID's reported by blkid and mdadm? On one of our CentOS systems, for example: [root@server ~]# blkid | grep /dev/md1 /dev/md1: ...
7
votes
1answer
12k views

mdadm raid1 and what chunksize (or blocksize) on 4k drives?

I want to use two 3 TB drives in a mdadm raid1 setup (using Debian Sequeeze). The drives use 4k hardware sectors instead of the traditional 512 byte ones. I am a bit confused because on the one hand ...
3
votes
1answer
3k views

recovery data from RAID and disk failure (Linux)

Some background A friend of mine was using in his office a NAS Buffalo-LS-WVL with two disks of 1TB each. It seems that the two disks were mounted as raid 1, but, as you will read, probably they have ...
2
votes
1answer
379 views

Drive was unable to assemble into the array

I ran mdadm -A /dev/md0 /dev/sda1 /dev/sdb1 Only /dev/sdb1 was loaded into the array though. I have a few more arrays on the same two drives too. Each time the partition on sda failed. dmesg told ...
4
votes
2answers
4k views

What does mdadm's “spare” number mean?

I created a mdadm-based RAID 5 from six hard drives using the following command: # mdadm --create /dev/md0 --level=5 --raid-devices=5 \ /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 \ ...
2
votes
2answers
189 views

raid5 exchange 1 of 3 harddrives [duplicate]

I want to exchange a Harddrive which is in a pre-failing state, (some reallocated sectors) which is used in a raid5 array with 3 disks (software raid with mdadm). Is it possible to set a new ...
2
votes
1answer
998 views

convert /dev/md0 to /dev/sda1

I used a Software-RAID I and want to access the data without RAID now. After mdadm --fail /dev/md0 /dev/sda1 mdadm --remove /dev/md0 /dev/sda1 I tried mount -t ext4 /dev/sda1 /mnt but dmesg ...
1
vote
1answer
109 views

mixed raid types

I am about to reinitialise my (SW) raid array. Previously the array was raid5 with 4 disks. I've removed one disk in order to install a new additional (larger) drive. What I'd ideally like to do is ...
0
votes
0answers
2k views

Linux md RAID: /dev/md0 vs. /dev/md/0

On newer systems /usr/share/mdadm/mkconf (the script that is used to generate /etc/mdadm/mdadm.conf) tends to use the device name /dev/md/0 instead of /dev/md0: new-system ~ # /usr/share/mdadm/mkconf ...