RAID - Redundant Array of Independent Disks. A Storage technology to provide redundancy and performance, to reduce I/O bottlenecks involved in using multiple disks for large storage.

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How to check mdadm raids while running?

I'm starting to get a collection of computers at home and to support them I have my "server" linux box running a raid array. Its currently mdadm raid1, going to raid5 once I have more drives (and ...
10
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2answers
5k views

Whats the difference between mdadm state “active” and state “clean”

I two different computers with different RAID5 arrays. When I run the command mdadm --detail /dev/md0 one drive reports "active" while the other reports "clean" for the "state" field. What is ...
9
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2answers
941 views

Choosing filesystem for a 16TB Raid

I'm just putting together a machine with eight 2TB disks. I will be using Raid 6 (12TB of usable capacity) on top of them, but I'm not sure whether I should make LVM on top of the RAID, or what ...
7
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2answers
490 views

In place upgrade of a software raid 5 array

I run a software raid array for my backups, but my data has outgrown capacity. considering I have a full 2.4TB array with 5*600GB drives and also have 5*2TB drives I would like to swap in. What ...
7
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1answer
523 views

bit rot detection and correction with mdadm

I'm about to re-organise all my HDDs in my linux box nas and would like to use mdadm raid for data protection and its flexibility for reshaping the arrays. However, before I use mdadm for this I'd ...
7
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1answer
6k views

How to mount a disk from destroyed raid system?

I have a horrible situation where I have to restore data from damaged raid system in a rescue Debian Linux. I just want to mount them all to /mnt/rescue in read only modus to be able to copy VMWare ...
7
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0answers
280 views

LVM: Couldn't fill logical volume maps

So I have a big problem here. On our server, there is an LVM raid with one volume group called raid. It contained two volumes, secured and unsecured and some unallocated space. Today I tried to remove ...
6
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1answer
2k views

mdadm Raid5 gives spares missing events

I succesfully builded up a raid5 array on debian testing (Wheezy). As the manpages and further tell, the array would be created as an out of sync array with just a new spare injected to be repaired. ...
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6answers
2k views

Pros and cons of software Parity-RAID (e.g. RAID5)

I was recently told about some problems concerning Parity-RAIDs without a non-volatile cache. More exspensive HW-controllers do have battery-powered caches to finish write-operations in case of power ...
6
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2answers
1k 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 ...
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votes
5answers
872 views

Consumer Level software RAID5 and LVM

Hi I am going to build a 6 drive consumer level RAID 5 (10TB) with Ubuntu10.10 and using EXT4 as filesystem, and OS on another drive. Question: Should you use LVM on top of the RAID5 or should just ...
5
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3answers
3k views

Mounting multiple devices at a single mount point on Linux

Is there a way to mount multiple hard drives to a single mount point? Let's say I run out of space on /home and decide to add an extra hard drive to the computer. How do I scale the space on a mount ...
5
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2answers
232 views

RAID 5 with 4 disks fails to operate with one failed disk?

I found a question about mdadm spare disks which almost answers my question, but it isn't clear to me what is happening. We have a RAID5 set up with 4 disks - and all are labeled in normal operation ...
5
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3answers
2k views

Using mdam --examine to write mdadm.conf

I'm trying to script the RAID setup for a (growing) number of identical servers. The advice I've seen for using mdadm suggests that once the RAID array has been created you can run mdadm --examine ...
4
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2answers
136 views

Where did 47gigabytes of space go?

Clean installation od Debian squeeze 6.0.6 x64 on intel atom 230, with 3 HDDs, with 3x500GB. df -h shows : datastore size used free % mounted /dev/md0 917G 909M 870G ...
4
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3answers
333 views

What would be a good choice for an elastic file system (for adding storage at a later date)?

I'm currently running a Debian 6.0 server with EXT3, but I'd like to move over to Arch. It's being used as a file server right now with a 1TB drive in it (of which 650GB in it is used). What I'd like ...
4
votes
2answers
139 views

RAID setups questions

I have a RAID setup questions My mobo supports hardware RAID, my question is, should I use the board's RAID system or freeNAS/Ubuntu's software RAID system? I realize performance is better with h/w, ...
4
votes
1answer
631 views

Unable to mount raid on my NAS, trying to rescue the data, how should I proceed?

A short backstory: something happened on my Synology NAS, apparently a buggy mailserver program that came with an update stopped the device from seeing the 2x3TB drives I have. After a lot of ...
4
votes
3answers
448 views

mdadm with overlaying lvm - remove a hard drive

This is a hypothetical question, I'm just evaluating in which way I should configure my hard drives for my home-server and for that I need to know this: Let's say I have a Raid5 configured with mdadm ...
4
votes
1answer
131 views

ext4 directory lists as a file

I'm working with a large (8TB) EXT4 filesystem in linux. After a power outage, the filesystem wouldn't mount. fsck is taking weeks to complete, but i ran testdisk and i'm able to see my partition ...
4
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1answer
88 views

Reusing older raid discs

I have a software RAID5 array (Linux md) on 4 disks; the OS is OpenSUSE 12.3. Recently I replaced a disc with a larger one (fail disc, remove it, add new disc). The capacity of the array has not yet ...
4
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3answers
1k views

Partitioning EFI machine with two SSD disks in mirror

I have two SSD disks, I want to put them in a software mirror RAID. But whatever I do the OpenSuSe installation keeps telling me that due to the partitioning scheme he won't be able to install the ...
4
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1answer
450 views

Alternatives to LVM

I was thinking about alternatives to combine several HDDs together. The only options I know so far are using LVM and/or RAID. The thing is, using LVM, I will most probably lose all data, if one ...
4
votes
1answer
2k views

Linux: LUKS and multiple hard drives

I have a Debian Linux system (amd64) installed on a RAID-1 system encrypted device (LVM on LUKS) and will have a RAID-6 of >=4 disks where I'll put my data (LUKS and maybe LVM). I think the basic ...
4
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1answer
1k views

RAID 10 can not be started

I have a RAID 10 array managed with mdadm which has failed . The symptom was that X has crashed and I was unable to logon from the terminal. I have restarted the computer and /dev/md1 did not start. ...
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2answers
499 views

Linux software RAID-1 and device name

I want to set up software RAID-1 on my Ubuntu system, and found this example of an /etc/raidtab: raiddev /dev/md0 raid-level 1 nr-raid-disks 2 nr-spare-disks 0 ...
3
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1answer
1k views

Why does btrfs allow to create a raid1 with mismatched drives?

I'm creating a btrfs using sudo mkfs.btrfs -m raid1 -d raid1 <small-disk> <large-disk> or sudo mkfs.btrfs -m raid1 -d raid1 <large-disk> <small-disk> it creates the fs with ...
3
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2answers
183 views

Is a ZFS storage array portable across operating systems & CPU Architectures?

I know that ZFS is available on variety of operating systems Solaris, Illumos, Linux, BSD etc. Suppose I have a bunch of disks that are part of ZFS raid file system that was created on Linux, could ...
3
votes
1answer
735 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 ...
3
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3answers
61 views

Recovering data from a failing RAID 5 setup

I have a four disk RAID 5 array that is in the process of failing hard. One disk is completely dead and smartctl is telling me that a second disk is failing. All the data on the RAID is backed up, ...
3
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1answer
31 views

understanding the “chunk size” in context of RAID

Am I correct that chunk size in context of RAID is essentially the same thing as cluster in file-system context? In other words, chunk size is the smallest unit of data which can be written to a ...
3
votes
3answers
818 views

Is creating a sparse image using dd appropriate for backup/restore from a RAID?

I have two non-networked servers, each with 1.2TB of storage in a RAID5 config on an LSI MegaRaid 9240-8i controller. I have been trying without success to get Symantec Ghost to image one machine to ...
3
votes
3answers
935 views

Avoid pause during dm-raid initialization

On my CentOS 5 workstation I get a few seconds wait after dm-raid45 has been loaded ("Initializing Driver" or something like that). This seems to be part of the initrd. After that the system boots ...
3
votes
1answer
152 views

mdadm; previously working; after “failure”, cannot join array due to disk size

Abstract I had a functional Raid 5 array, I rebooted the box, and then mdadm couldn't re-assamble one part. Seeing that it was only one part, I thought it would be easy to just re-sync. But that ...
3
votes
2answers
121 views

View Files from mirrored RAID outside the device

The Product I have is a Western Digital My Book The device has stopped working but there is nothing wrong with either of the two mirrored drives. I would like to take out the two mirrored hard ...
3
votes
2answers
85 views

Grow LVM RAID10?

RHEL LVM has supported RAID4/5/6 as of 6.3 and RAID10 as of 6.4. It's well-known that mdadm won't let you --grow raid10, my question is whether this is a limitation of LVM RAID10 too? If it is ...
3
votes
1answer
1k views

New md array is auto-read-only and has resync=PENDING

I've created a new md array with the following command: mdadm --create /dev/md1 -l 1 -n 2 /dev/sd[ed]1 But now /proc/mdstat shows the array as "auto-read-only" with resync=PENDING: ~ # cat ...
3
votes
1answer
203 views

How to remove disk from RAID1 without knowing the /dev/XXX name?

BEFORE: SERVER:~ # mdadm --detail /dev/md5 /dev/md5: Version : 00.90.00 Creation Time : Fri Mar 18 14:53:33 2011 Raid Level : raid1 Array Size : 67103360 (63.99 GiB 68.71 GB) ...
3
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1answer
1k views

installing grub 2 on mdadm, which device?

when installing grub(2) to mdadm devices are you supposed to install it to /dev/sdX or /dev/mdX?
3
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0answers
111 views

What happens if I delete dmraid?

I am new to Linux and am trying to install Ubuntu 12.04.3 LTS from a live-USB and have it run alongside my Windows 7 installation. On the installation screen for Ubuntu, at the partition page, I get ...
3
votes
1answer
316 views

cleaning /dev/md0 filesystem ( raid)

I have a CentOS server using raid. The /proc/partitions contains: major minor #blocks name 8 0 976762584 sda 8 1 104391 sda1 8 2 921600855 sda2 8 3 55054755 ...
3
votes
2answers
128 views

RAID Lag-Behind Burst Write

I would like to setup RAID1 so that a ramdisk in the RAID configuration has occasional synchronisation with a physical disk (that is very battery intensive to run, so I hope to let it spinout). Is ...
2
votes
2answers
928 views

Very slow SW-RAID 5 in Debian Squeeze

I don't know why, but I have big trouble with speed of my raid. I have 4x WD RE4 7200RPM 500GB. Size of RAID 5 is 1000GB. 1 of HDDs is Spare. Problem is here: Every 1,0s: cat /proc/mdstat ...
2
votes
1answer
118 views

How to setup a RAID system using USB sticks as storage media

I want to create an inexpensive self-hosted private git server with redundant storage. To that end I have bought a Raspberry Pi and configured both git and ssh on the Pi. I can access the Pi both from ...
2
votes
3answers
2k views

Can I create a software RAID 1 with one device

I have a single disk that I want to create a Mirror of, Lets call this disk sda I have just bought another identicle size disk, which we can call sdb. sda and sdb have one partition called sda1 and ...
2
votes
2answers
109 views

Are disks interchangeable in a mirrored RAID setup?

It is often written that disks in a mirrored RAID (like RAID 1) are an exact mirror copy one of another. So can I turn the machine off and simply swap the two harddisks cables? And if one of the two ...
2
votes
2answers
957 views

Strange error message during CentOS 6.5 installation regarding disk containing BIOS RAID metadata?

While attempting to use an old 40GB HDD to setup a kind of junky though usable Athon 1GHz system I ran into the following error during the HDD identification/partitioning phase of the installation: ...
2
votes
1answer
1k views

Interpreting tiobench results

I'm running tiobench on my raid1 and it gives me the following results. Why is there ##### shown instead of throughput? Why does seq.reading with 8 threads use 2836% CPU? My results: $tiobench No ...
2
votes
1answer
113 views

mdadm - RAID5 array size vs. actual disk size mismatch

I have 4x 3TB WD RED disks that are in mdadm RAID5, which should total an array size of 9TB usable space, however I only have 6TB. I have confirmed all disks are in the array, the only strange thing ...
2
votes
2answers
321 views

Best way to create RAID on an existing system drive

I want to add another disk as RAID 1 to test my database performance. I am trying to not re-do the whole system, is it possible? Currently I have a single 1TB HDD with one 100GB system partition (and ...