Ubuntu Servers :: Recovering A Three Disk Software RAID 5
Mar 12, 2011
I'm testing my ability to recover a failed disk on a three disk software RAID 5 setup.
I have used a 10.04 alternate install disk to setup a three disk RAID 5 array according to this: [URL]. This is for a RAID1 setup. I followed it exactly except that I performed the steps on three drives rather than two and selected RAID5 instead of RAID1. Each disk is 500GB and has a 26 GB swap partition and the remaining space on each disk set as / with the boot flag on.
I installed the OS on my array and everything boots without a problem. After I booted up I started a terminal and ransudo dpkg-reconfigure mdadm to set the boot degraded to true and rebooted.
Next, I shut down the computer, disconnected the power on drive 1 (sdb) and then tried to boot. I get this (not verbatim):
Quote:
mdadm: CREATE user root not found
mdadm: CREATE group disk not found
raid5: raid level 5 set md0 active with 2 out of 3 devices, algorithm 2
mdadm: /dev/md0 has been started with 2 drives (out of 3)
[Code].....
*then a list of common problems and then:
ALERT! /dev/disk/by-uuid/bunchanumbersnad letters does not exist. Dropping to a shell
Then it dumps me to initramfs. MD0 is the swap partition. At this point I don't know what the heck to do. I'm skating on the edge of noobidity and this is pretty much over my head.
I want to use this server as a virtual machine server and the desired behavior would be that, if a hard drive should fail, the server would alert me via email and continue to run in a degraded state.
Is it even possible to install the OS on the array and run it degraded? Given the desired behavior, should I be looking at something other than RAID5? My client is broke so I'm trying to avoid a hardware RAID if I can do it.
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Jan 3, 2009
I had a RAID1 'device' build on two physical partitions on two drives. One of the disk controllers died and software RAID did the job - now I am working on the degraded array.
Now I want to put the old disk (sdb) back, and I am not sure what will happen. Both disks have 'raid auto' partitions. And sdb file structure from before of the failure. The raid code will find inconsistency between both partitions. What will it decide? Will it start coping from the currently running system (sda) all the data to the old one (sdb) at the boot time, as I wish?
I don't want to it to write from the old one to the new one, as some months passed and lots of changes happened to the data.
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Jun 28, 2010
I have an SiI hardware SATA RAID card, with two 500GB disks in mirrored RAID configuration. When I first plugged them in and set it up, things seemed to work ok, but on boot the raid controller told me that the RAID needed rebuilding, and it would happen automatically after POST. So I didn't worry about it, and the drive mounted fine, and it's been that way for years. I just went in and manually on-line rebuilt the RAID in the controller's BIOS, and now when I boot into Ubuntu, both disks show up in fdisk, but neither show up in /dev/disk/by-uuid. Am I missing something?
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Apr 14, 2010
One of my raid disks (was a software raid5 with 4 drives) failured. I wanted to buy a new 1.5TB harddisk anyway so i i copied all the Raid data onto the new disk and disconnected the old ones. But then the new Disc crashed right before i could mirror it with another 1.5TB disk. So i need to reassemble my old Raid 5 now. I connected the drives in the former order except the first one, because this was the failed disk. The problem is, mdadm can't find the raid, no superblocks. Fdisk doesnt show mdraid superblocks, too. But fdisk has never showed superblocks. The thing is, this raid was crypted, but i crypted the /dev/md0, so this doesn't affect anything here, or?
some infos:
Code:
server:~# mdadm --misc -d /dev/sda
mdadm: option -d not valid in misc mode
server:~# mdadm --misc -t /dev/sda
[code]....
Disk /dev/sdc doesn't contain a valid partition table But fdisk always said there is no valid partition table and the raid was working.
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Nov 23, 2010
My raid array has failed. I have two disks /dev/sda and /dev/sdb./dev/sdb has failed and I could not rebuild the array(madm returned that the device is busy) so I rebooted the machine. After that, the whole sdb disk went missing, as it now only shows sda in fdisk -l.Did the disk went totally dead or my raid glitched?
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May 5, 2011
My system locked up while copying files last night. My RAID array will not start. I did verify my UUID's. (Lesson learned.) I do not understand a few things.1. Why do different drives show "active sync" on different drives? 2. Why does "Disk Utility" tell me the RAID is not running and when I try to assemble the RAID, mdadm returns: mdadm: device /dev/md0 already active - cannot assemble itWhen I try to start the RAID using "Disk Utility":
Code:
Error assembling array: mdadm exited with exit code 1: mdadm: cannot open device /dev/sdd1: Device or resource busy
mdadm: /dev/sdd1 has no superblock - assembly aborted
So, I examine sdd1:
Code:
sudo mdadm -E /dev/sdd1
[Code]...
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Jun 7, 2010
I'm looking to set up a bit of a home server, and am wondering about storage. What I'd like is something like RAID 6, which has good redundancy built-in, but with this being a home server, I'd prefer to start a little smaller and leave room to build it up in future. I'd been looking at commercial products like the 'drobo', which seems fairly ideal, but I'd really like to see if I can do it myself. I understand that throwing the RAID into an LVM will allow for some expansion, but the last time I checked, most RAID setups called for the same sized disks, or at least limited the array by the size of the smallest disk present.
What I'd like is the ability to build a basic framework with a few cheap disks, and then as things start filling up, to be able to add larger ones (perhaps eventually pulling out smaller ones as though they'd failed and replacing them with big ones)
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Aug 11, 2010
So I've pulled two hard drives out of my busted windows xp system (dead mb) and I'm trying to get some data off of them. The drives are in raid 0, so my friend told me that I might be able to do something if I use linux. Some late night searching on the internet directed me to a few resources, one of which was this forum. I've tried 2 methods, neither of which have worked.
1. mdadm
ubuntu@ubuntu:~$ sudo mdadm --detail /dev/sdb
mdadm: /dev/sdb does not appear to be an md device
2. dmraid
ubuntu@ubuntu:~$ sudo dmraid -s
/dev/sdb: "sil" and "hpt45x" formats discovered (using hpt45x)!
ERROR: sil: wrong # of devices in RAID set "sil_agafdhcebccj" [1/2] on /dev/sda
ERROR: removing inconsistent RAID set "sil_agafdhcebccj"
[code]....
I've got some files for work that I'd really like to get off there. I've played with unix a bit in college and I've ran ubuntu before, but usually using the GUI, so a lot of this stuff is over my head. But from what I gather, my system thinks that one of the drives isn't a raid drive?
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Jan 9, 2011
I've got a raid5 array of 4 disks with ubuntu 8.04 runing on it that is currently still working:
/dev/sda
/dev/sdb
/dev/sdc
/dev/sdd
Smartmontools for /dev/sdc tell that there are 9 sectors pending for reallocation:
Code:
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 9
198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 9
And /dev/sdd has increasing number of reallocated sectors (about 1 every couple of minutes):
Code:
5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 1735
/dev/sdc has failed a coulple of times this week (but I have always sucessfully readded it to raid5) . But the increasing number of reallocated sectores on /dev/sdd concerns me even more.
I'm affraid that during removal of /dev/sdd and adding new /devs/sdd disk, raid might fall appart. That's why I would try to do it in Ubuntu Live CD:If the raid falls appart (/dev/sdc fails) during the readding of new /dev/sdd disk, I might still remove the new /dev/sdd and return the previous one and assemble the raid with:
/dev/sda
/dev/sdb
/dev/sdd (old one that was previously removed)
Does assembling Raid in Ubuntu Live and adding new disk for /dev/sdd write anything on /dev/sda, /dev/sdb and /dev/sdc in the process of adding /dev/sdd into raid5?
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Feb 1, 2011
Could any RAID gurus kindly assist me on the following RAID-5 issue?I have an mdadm-created RAID5 array consisting of 4 discs. One of the discs was dropping out, so I decided to replace it. Somehow, this went terribly wrong and I succeeded in marking two of the drives as faulty, and the re-adding them as spare.
Now the array is (logically) no longer able to start:
mdadm: Not enough devices to start the array.Degraded and can't create RAID ,auto stop RAID [md1]
I was able to examine the disks though:
Code:
root@127.0.0.1:/etc# mdadm --examine /dev/sdb2
/dev/sdb2:
Magic : a92b4efc
Version : 00.90.00
code....
Code:
mdadm --create --assume-clean --level=5 --raid-devices=4 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2
As I don't want to ruin the maybe small chance I have left to rescue my data, I would like to hear the input of this wise community.
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Jun 3, 2010
After a disastrous upgrade to 10.04 I am at my wits end trying to recover my /home partition from my unbootable system. The /home partition is part of a RAID5 array across 4 disks and I've been trying to use some disk imaging tools from Ultimate Boot CD to recover it with, but none of the utilities seem to recognize or will let me work with my multi-disk device.
Currently I've been booting up with a Live CD in attempts to mount the encrypted partition then copy all the files to an external device I bought, but the mounting process has presented me with some problems. The partition in encrypted with ecryptfs and I have both the disk's passphrase as well as an FNEK signature to work with. Attempting the following:
Code:
Another small issue is the cipher I used. I don't remember which kind of encryption the disk is encrypted with (80% sure it's aes though). I assume figuring out which cipher I used will be more like a guessing game through the ecryptfs mount prompt, but I'm wondering if this would affect the error message I get.
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Jun 30, 2011
I recognize that this isn't the typical question, but I have a problem with my OpenSUSE webserver, and I thought I would prevail on the community for some guidance. I have this webserver with an important MySQL db on it. The RAID array seems to have died while I was moving. (did someone drop it? dunno) Now it can't find any boot device. It has 4 old SCSI drives.
So, I know how to mount a IDE or SATA drive as a slave, in a Linux environment to read data off of it (to copy the MySQL files off of it.) But, how do I do that with a SCSI drive? Also, I have an additional (identical) server to the crippled one. What will happen if I just slide one of the scsi drives into the operating server? Is this second identical server going to help me at all? I don't even know what is on it. Can I reconfigure the RAID, so it's not using a drive, and then slide in a disk from the crippled server, and copy the data off of it?
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Sep 27, 2010
I have a NETGEAR ReadyNAS NV+ with four 1TB drives in a RAID-5 array. This is our primary file storage. This has previously been backed up to a hardware RAID-0 array directly attached to our Windows server. The capacity of this backup array is no longer sufficient. So the plan was, take a bunch of 200GB to 320GB drives (And a 750) I had kicking around, chuck them in a couple of old SCSI drive enclosures I have collecting dust, attach them via IDA/SATA-to-USB adaptors to a USB hub, attach that to the server, create a JBOD array spanning the disks, and back up the NAS to that. Performance is not an issue as this is just to be used for backup, with the idea being as near to zero cost as possible (Spend so far = NZ$100�ish).
The first hurdle I struck was Windows not supporting Dynamic Disks on USB drives (Required to create a spanned volume). At first I resisted using another machine (i.e. a machine running Ubuntu) as I didn't want to dedicate a piece of hardware to backing up the NAS. I then decided it would be acceptable to do this via a VM, which is what I've done.So I have 10.04 running under VMWare Server 2.0.2 under Windows Server 2008 R2. The disks are all presented to the VM. I wasn't sure if I was going to end up creating the array under LVM or something else, but I noticed Disk Utility has an option to create an array, so I tried that. When I add two 250GB drives, the array size is 500GB. When I then add a 160GB drive, the array size drops to 480GB. Huh? If I keep adding disks (Regardless of order) the final array size comes out at 1.8 TB, as per the attached screenshot. Now with the following drives, I expected something more like:
160 + 250 + 250+ 750 + 250 +200 + 200 + 250 + 320 + 250 + 320 = 3.2TB
Am I missing something or making a false assumption somewhere?
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Jan 19, 2011
I have 2 RAID1 hard drives with possibly hardware errors, (when I tried to mount them in a degraded array, they won't start, throwing some Buffer I/O errors) So I used ddrescue to make a disk image out of one drive, ran losetup to use the image file as loopback device:
Code:
losetup /dev/loop0 imagefile.img
but when I tried to assemble a raid array including the /dev/loop0 device like:
Code:
mdadm --assemble /dev/md0 --force /dev/loop0
it will complain that no superblock is found on /dev/loop0 device. With desperation, I tried to create a legacy raid array with following command, of course, including one of the bad drives:
Code:
mdadm -B /dev/md0 --level=1 -n2 /dev/sdb1(bootable partition on the bad drive) /dev/loop0
I successfully created a new RAID1 array, but when I tried to mount it
[Code]....
Now the only thing I haven't tried is to clean the superblock by doing --zero-superblock, and not sure if that will solve the problem. Should I get a second drive to hold my broken drive image so that I might be able to assemble a good RAID1 array or should I continue working on the only disk image file I recovered from one of the broken drives?
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Jul 16, 2010
I learned a couple of days ago why you should do regular backups. Left my laptop working for the day in hot weather. When I came back it had crashed. On reboot it no longer booted up. I could still access the BIOS and boot from alternative media but not from the hard drive. The laptop tried to access the hard disk for a couple of minutes (hard drive light was blinking) and then failed. I made an ubuntu live usb stick and am currently working from there, trying to access my hard drive so I could image my data on another disk before sending the laptop for repairs. All my data is on that disk including my passwords and the password for this site conveniently so I had to register a new account to post this thread.
The laptop is IBM Thinkpad X41. The hard drive is accessed during when boot options are presented, again when the live cd boots up and determines the hardware available and also when manually probing for hard disks using the script below. The hard disk however does not show up in dev. If I could get so far to get it there, I could use dd_rescue to image it away. My hope lies in that the drive still spins up and is accessed producing error messages, however indicating that the system still knows it exists. Excerpt from dmesg concerning the drive:
[Code].....
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Jan 2, 2011
I have a few hard disks fully encrypted with Truecrypt. They have not been partitioned, just encoded right of the bat with Truecrypt. I just use Truecrypt command line to mount them, supplying password whe asked.
So from a linux standpoint, they show up as disks with unallocated space.
But I recently updated (moved) my linux from Ubuntu to Kubuntu. In the process, the partition manager asked where to install the new OS, I answered erase existing system and install there. But I noticed too late that the install program decided to install GRUB on another disk, one of my encrypted disks, instead of the system disk already selected. I don't know why, but it did. Now this disk shows up in linux as a disk with multiple partitions, and of course I can no longer mount it with Truecrypt.
I haven't done anything with the disk, except from trying to mount it in Truecrypt. So apart from the GRUB install, nothing else was touched on the disk.
I know Truecrypt place a backup header towards the end of the encrypted disk, so it should still be there intact, but since I now have multiple partitions, Truecrypt is certainly confused and cannot see the end of the disk since I now have 4 of them (partitions).
I am not a beginner but I am hesitant to attempt something that could kill all hopes of recovering the disk. It is a 2TB disk with a lot of data on it. I could probably make a copy of the entire disk but this means buying another 2TB disk....
One of the first idea was to kill the current partition setup to leave it "unpartitionned", so like it was before, maybe Truecrypt will now find the backup header. But before I do so, I would like opinion of real experts on linux.
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Aug 1, 2010
I had done a new lucid install to a 1 TB RAID 1 array using the alternate CD a few weeks back. I messed up that system trying to some hardware working that lucid doesn't have drivers for yet, so I gave up on it and reinstalled to a single 80 GB disk that I now want to move over to the RAID array.
I moved all of the existing files on the array to a single folder, then copied all of the folders from the 80 GB disk over to the array with permissions and symlinks (minus the contents of /proc and /sys, which I created empty).
These are the commands I used:
Quote:
p -a -d -R -v -t /media/raid_array /b*
cp -a -d -R -v -t /media/raid_array /d*
cp -a -d -R -v -t /media/raid_array /e*
cp -a -d -R -v -t /media/raid_array /h*
[Code]....
I tried to change fstab to use the 689a... for root, but when I try to boot, it's still trying to open /dev/disk/by-uuid/412d...
So then I booted from the single disk again and chrooted into the array, then ran update-initramfs -u. I got 3 "grep: /proc/modules: No such file or directory" errors, and "cat: /proc/cmdline: No such file or directory"- so I created directory /proc/modules, created an empty file /proc/cmdline, and ran the initramfs update again. Then I tried to shut down, which hung (probably because I was doing all of this from a terminal window in Gnome), so I killed the power after a couple of minutes.
It's still trying to use /dev/disk/by-uuid/412d... to boot.
What am I missing? I assume I just have to change the UUID to mount as root, but I don't know how.
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May 10, 2011
I was installing Ubuntu to the internal disk in my main machine, with all external drives unplugged for safety - then discovered I had accidentally chosen the external drive and it wasn't unplugged. (Seeing three drives not two listed as installation targets should have tipped me off, but I guess my IQ was low that day.)The external drive, in compliance with Murphy's Law, was my backup drive with all vital current files.The last few months of work gone.Now the drive shows only the stuff I normally expect in / on any Linux machine. It mounts showing as ext4, but the disk was (I'm 98.5% sure) originally ext3.However, the installation did not finish.Whatever files got copied, clobbered only a fraction of the disk. df reports only 1% of the space used.Maybe the bulk of my valuable files are okay, and could be recovered with some tool?
There are other questions on this site about file recovery, but many are for Microsoft Windows, or for malfunctioning disks, or some other situation. I'm on Linux with a physically healthy external disk. I'm fairly sure that the more recent and more important files are in multiple copies on that disk, so if one copy is clobbered there's hope to get the second copy.
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Oct 16, 2009
my Fedora 11 system is not starting anylonger. It stops with the message:
Code:
VFS: Can't find ext4 filesystem on dev dm-0
The system told me since a while, that a lot of the sectors of one disk of the (software) RAID compound are failed already. So tried to disconnect each of the disks and start them separately. Unfortunaltly this is not working (for one its is not working at all, the other wents the same far as with both), when I tried to recover the system with the Fedora DVD, it said no distribution found. I am quite new and do not know so much about linux system, so i do not know what further information you could need. Maybe it can be important, that both disks are encryped (the system wents so far, that I can type in the password).
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Mar 12, 2010
Today I wanted to make a backup of my Ubuntu server. Since the program wasn't working for me, I rebooted my computer and right now it wont boot. Now I entered recovery mode and I'm trying to recover my /var/www and /etc/mrtg folders. I want to copy them to my USB-Stick but Ubuntu wont do this.
The command I tried: Code: cp -r /var/www /dev/sdg1/www I already created the folder via a other system. I also tried to mount the USB stick: Code: mount /dev/sdg1 /mnt/usbe But im getting the following error: error while loading shared libraries: /lib/libsepol.so.1: Invalid ELF header.
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May 5, 2010
I was previously running postgresql 8.3, but upgrading to Ubuntu 10.04, has installed postgresql 8.4 and I'm now unable to start 8.3. I don't mind using 8.4, but I need to recover the data from my 8.3 installation, But I'm not sure how to do this as I can't start the 8.3 server, and 8.4 can't read my old data directory.
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Jul 17, 2010
point me in the direction to get a step by step guide to setting up a Raid 5 using the Disk Utility and 3 spare drives? I have the main OS files on a 80gig drive and I would like to mount the 3 drives as Raid 5.Just shooting in the dark now.. Screen shot is attached. [URL]...
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Jul 20, 2011
Has anybody ever used Disk Utility to set up software RAID? Here I am running terminal commands (I'm a terminal junkie) and I just happen to stumble across instructions that indicate "Or you can just set it up through Disk Utility."
Sure enough in disk utility, it looks like all of the configurable options are there. It makes me wonder, though... is this kind of GUI functionality something that isn't really solid? Or does it operate predictably and effectively?
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Feb 2, 2010
Recently, one the SMART utility said that one of the drives had failed and another drive was about to fail. I downed the box and hooked them up to my windows machine to run sea tools on them (They are all seagate drives). Sea Tools said that the drives were fine, while ubuntu said they were failing/dead. Yesterday I decided to try to fix one of the drives in the raid. I turned the server off, took the failed drive out, and restarted. Of course the raid didn't work because only 2 of the 3 drives were there, however it had been working w/ only 2 of the 3 drives for a couple months now (I'm a lazy college student). I turned it back off and back on with the drive there just to see if I could get the raid up again, but I havn't been able to get it to go. So far I've tried:
Code:
mdadm --assemble /dev/md0 /dev/sd[b,c,d]
mdadm: no recogniseable superblock on /dev/sdb
mdadm: /dev/sdb has no superblock - assembly aborted
[code]....
I'm looking for a way to trick the raid into working with just 2 drives until I can warranty the seagate and buy an external 1.5 TB drive to use as another backup. how to remove the bad drive from the array and replace it with a fresh drive, without data loss.
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Feb 25, 2010
i am currently trying to do software raid 1 on a running ubuntu 9.10 system with mdadm. I might have done something wrong and im trying to go back from the beginning. Does anyone know how to remove all the raid info from a harddisk and get it back to its original state.
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Mar 10, 2010
I want to install Ubuntu x86_64 or x86 to my computer.
I used Dekstop and Server Editions on other machines, installed succesfully but i could not install Ubuntu to my computer.
My hardwares are;
AMD Phenom II X4
Gigabyte GA-MA790GP-DS4h [SB750 - AMD AHCI Compatible RAID Controller]
2 x 250GB Seagate ST3250410AS @ Raid0
I installed Windows succesfully and i created 50GB partition for Ubuntu.
I tried to install Ubuntu, but disks are not detected in partition managing screen.
how can i install ubuntu?
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Mar 24, 2010
My system is installed on my main hd. Is possibile, if i buy a new hd, to setup a Software RAID, so with old and new hd without reinstall ubuntu?
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Jun 18, 2010
I have a fileserver which is running Ubuntu Server 6.10. I had a RAID5 array consisting of the following disks:
Code:
/dev/sda1
/dev/sdb1
/dev/sdd1
/dev/md0 -
the raid drive for the above three disks. The sda1 disk has failed and the array is running on 2 of 3 disks
/dev/sdc (OS disk)
/dev/sde (new 2tb disk - unused)
/dev/sdf (new 2tb disk - unused)
My plan was to rebuild the array using the two new disks as RAID1. Would the best way to do this be to create a new RAID1 disk on /dev/md1 then copy all data over from /dev/md0? Also - this may sound stupid but since all 3 drives in md0 are identical i'm not sure physically which disk is bad. I tried disconnecting each disk one-by-one then rebooting but the system doesn't appear to want to boot without the bad drive connected. I've already failed the disk in the array with mdadm but i'm unsure of how to remove it properly.
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Jul 8, 2010
What is the best way to install Windows and Linux on two-hard-disk array? In fakeraid there are no problems in Win, but linux installation is almost impossible (i've tried unsuccessfully...). In software raid it would be impossible to share files between win and linux? And finally hardware raid is possible, but cheap controllers have low performance. Is there any other way (apart from spending a lot of $$ for adaptec controller) ?
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Dec 19, 2010
I went to setup my linux box and found that the OS drive had finally died. It was an extremely old WD raptor drive in a hot box full of drives so it was really only a matter of time before it just quit on me. Normally this wouldn't be such a big deal however I had just recently constructed an md RAID5 array of 3 1TB disks to act as an NFS mount for basically all of my important files. Maybe 2-3 weeks before the failure I had finished moving all of my most important stuff onto that array. Now I know that the array is intact. All the required data is sitting on those disks. Since only the OS level disk failed on me I should be able to get a new disk in there, reinstall ubuntu and then rebuild that array. how exactly do I go about doing that with mdadm? Do I create the array from the /dev character devices like when I initially built the array?
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