To answer your questions, Can it be restored? First thing’s first – STOP, sit back and just think a little. Yes, algorithm, chunk size and disk order is vital to getting whatever filesystem that was present, to properly re-assemble. But since you’ve overwritten the superblocks, you’re now left with trial and error. Second, is there … Read more
I want to extend suggestions above. It is extremly worth setting up overlay block device, so any changes to the file system that you’ll do in attempt to recover it will not change anything on the RAID and this will allow you to reset everything and start from the beginning. Therefore, you’ll be given infinite … Read more
First of all: to those, who still believes in “RAID0 has no hot spare”. It could have a manual spare, done by human, who understand RAID levels and mdadm. mdadm is software RAID, so it could do a lot of interesting things. Credits to Zoredache for the idea! So, the situation: you have RAID0 array … Read more
cat /proc/mdstat will give you the output you need, relatively easy to parse, because the mapped device is on the same line as its members, e.g.: $ cat /proc/mdstat Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [linear] [multipath] md0 : active raid1 sdf2[1] sde2[0] 81854336 blocks super 1.2 [2/2] [UU] md127 : active raid0 … Read more
Linux software RAID is not going to protect you from bit corruption and silent data corruption is a well known issue with it. In fact, if the kernel is able to read the data from one disk it would never know that it is bad. The RAID only kicks in if there is an I/O … Read more
Adding Back a RAID 1 Member To add a RAID member back into the array, use: mdadm <RAID Device> -a <Device to add into the array> For example: $ mdadm /dev/md0 -a /dev/sdc1 mdadm: re-added /dev/sdc1 If you check again using mdadm –detail , you’ll see that /dev/sdc1 is shown as “rebuilding”: Number Major Minor … Read more
Actually I think Wikipedia explains it better than the actual docs. Here’s the text from the article. The Linux kernel software RAID driver (called md, for “multiple device”) can be used to build a classic RAID 1+0 array, but also (since version 2.6.9) as a single level with some interesting extensions. The standard “near” layout, … Read more
The GRUB wiki confirms: Also, (as of 1.96+20080724) GRUB can only boot from RAID which uses a Version 0.90 metadata superblock (i.e. one created with the –metadata=0.90 option to mdadm). Curiously, the man page for mdadm says -e , –metadata= Declare the style of superblock (raid metadata) to be used. The default is 0.90 for … Read more
With linux softraid you can make a RAID 10 array with only two disks. Device names used below: md0 is the old array of type/level RAID1. md1 is the new array of type/level RAID10. sda1 and sdb2 are new, empty partitions (without data). sda2 and sdc1 are old partitions (with crucial data). Replace names to … Read more
You really kinda need the original mdadm.conf file. But, as you don’t have it, you’ll have to recreate it. First, before doing anything, read up on mdadm via its manual page. Why chance losing your data to a situation or command that you didn’t have a grasp on? That being said, this advice is at … Read more