2 Drives Failed: Seagate BlackArmor NAS 440 (Raid5)

[Geeksmirage]

1) RAID5/Z1 isn't double parity. RAID5/Z1 is single parity. RAID6/Z2 is double parity, RAIDZ3 is triple parity. I wouldn't think of either a RAID5 or a RAIDZ-whatever as a back-up necessarily. If you're storing backups of your workstation, or your HTPC media drive on the RAID, then yes, it is a backup. If you're storing all of your media on the RAID for access, then that is ipso facto, the master copy w/ some redundancy to improve availability and not a backup.

To be a proper back-up, you really want something that can protect you from NOT ONLY drive failures, but also from things like natural disasters (flood, fire, berserk SATA controllers), and human error/malice (i.e. not a RAID mirror that will blindly mirror said errors/malice). It should ideally have versioning, and be secured when a backup is not being made or they are being tested.

2) Compressed backups can work. They have the advantage of being relatively easy to do. They have the disadvantage of taking up lots of space quickly. It isn't very hard to write a script that uses rsync+hardlinks to create "snapshots" of filesystems. I'd be happy to send you a basic one if you PM me. There is even a utility called "rsnapshot" that does this out of the box! This could allow you to do incremental backups, and structure the incremental backups so that each snapshot looks like your whole filesystem. Versioning! Yay!

Edit:
This is kind of old/hokey, but it captures many of the ideas of what we mean by "backup".
http://www.taobackup.com/

Regd. RaidZ, I understand.

By compressed backups, Im actually trying to save space, so im not sure why it would take more space? Unless you cant do incremental backups with compressed backups.

E.g. If I backup 10GB, lets say it stores it compressed as 8GB. So I just saved 2GB. The issue is, next time is checks the folder for changes, will it detect the new 1GB file and compress that and add it? Or will it replace my entire backup...?

 

[Geeksmirage]

I finally got my computer up and running. Added the 4 RAID5 drives to it (Along with my

Windows SSD and a Liveboot USB.) Im running Ubuntu 14.04 LTS via Liveboot USB.

The problem is that mdadm is not detecting my RAID. As per my very limited understanding

and reading up, the Kernel is showing only RAID1 and not RAID5, hence its trying to mount

a RAID5 as 2xRAID1 and that obviously wont work.

I googled a lot for this solution, I wasnt able to find any solution for "how to see more

mdadm personalities".

I was following this guide:
https://www.synology.com/en-us/knowledgebase/faq/579

Any clue how I can see "Personalities : [raid1] [raid5]" instead of "Personalities :

[raid1]"? I assume once I can do that, then it will mount properly and I can take it from

there?

These are the outputs:
root@ubuntu:~# mdadm -Asf && vgchange -ay
mdadm: /dev/md0 has been started with 2 drives (out of 4).
mdadm: /dev/md1 has been started with 1 drive (out of 4).
mdadm: /dev/md2 has been started with 2 drives (out of 4).
mdadm: /dev/md/3 assembled from 2 drives - not enough to start the array.
mdadm: /dev/md/3 is already in use.



root@ubuntu:~# cat /proc/mdstat
Personalities : [raid1]
md3 : inactive sdc4[5](S) sda4[4](S)
5854919650 blocks super 1.2

md2 : active raid1 sdc3[1] sda3[3]
521408 blocks [4/2] [_U_U]

md1 : active raid1 sdc2[1]
1044800 blocks [4/1] [_U__]

md0 : active raid1 sdc1[1] sda1[3]
1043840 blocks [4/2] [_U_U]

unused devices: <none>


root@ubuntu:~# mdadm --detail /dev/md0
/dev/md0:
Version : 0.90
Creation Time : Sat May 18 06:56:32 2013
Raid Level : raid1
Array Size : 1043840 (1019.55 MiB 1068.89 MB)
Used Dev Size : 1043840 (1019.55 MiB 1068.89 MB)un
Raid Devices : 4
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Sun Dec 21 08:30:27 2014
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0

UUID : 7cda6052:0dc03e85:cd12dfca:1bf6aa0d
Events : 0.528145

Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 33 1 active sync /dev/sdc1
2 0 0 2 removed
3 8 1 3 active sync /dev/sda1



root@ubuntu:~# mdadm --detail /dev/md1
/dev/md1:
Version : 0.90
Creation Time : Sat May 18 06:56:33 2013
Raid Level : raid1
Array Size : 1044800 (1020.48 MiB 1069.88 MB)
Used Dev Size : 1044800 (1020.48 MiB 1069.88 MB)
Raid Devices : 4
Total Devices : 1
Preferred Minor : 1
Persistence : Superblock is persistent

Update Time : Mon Nov 17 01:00:27 2014
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0

UUID : 12ee366a:1f4fe8a2:b077ee83:99eef097
Events : 0.122

Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 34 1 active sync /dev/sdc2
2 0 0 2 removed
3 0 0 3 removed


root@ubuntu:~# mdadm --detail /dev/md2
/dev/md2:
Version : 0.90
Creation Time : Sat May 18 06:56:33 2013
Raid Level : raid1
Array Size : 521408 (509.27 MiB 533.92 MB)
Used Dev Size : 521408 (509.27 MiB 533.92 MB)
Raid Devices : 4
Total Devices : 2
Preferred Minor : 2
Persistence : Superblock is persistent

Update Time : Sun Dec 21 08:30:27 2014
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0

UUID : a1e3ca7f:18edb817:840561a4:03c82e37
Events : 0.166

Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 35 1 active sync /dev/sdc3
2 0 0 2 removed
3 8 3 3 active sync /dev/sda3


root@ubuntu:~# mdadm --detail /dev/md2
/dev/md2:
Version : 0.90
Creation Time : Sat May 18 06:56:33 2013
Raid Level : raid1
Array Size : 521408 (509.27 MiB 533.92 MB)
Used Dev Size : 521408 (509.27 MiB 533.92 MB)
Raid Devices : 4
Total Devices : 2
Preferred Minor : 2
Persistence : Superblock is persistent

Update Time : Sun Dec 21 08:30:27 2014
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0

UUID : a1e3ca7f:18edb817:840561a4:03c82e37
Events : 0.166

Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 35 1 active sync /dev/sdc3
2 0 0 2 removed
3 8 3 3 active sync /dev/sda3


root@ubuntu:~# mdadm --detail /dev/md3
mdadm: md device /dev/md3 does not appear to be active.



root@ubuntu:~# cat /etc/mdadm/mdadm.conf
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
#DEVICE partitions containers

# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# instruct the monitoring daemon where to send mail alerts
MAILADDR root

# definitions of existing MD arrays
ARRAY /dev/md0 UUID=7cda6052:0dc03e85:cd12dfca:1bf6aa0d
ARRAY /dev/md1 UUID=12ee366a:1f4fe8a2:b077ee83:99eef097
ARRAY /dev/md2 UUID=a1e3ca7f:18edb817:840561a4:03c82e37
ARRAY /dev/md/3 metadata=1.2 UUID=58fb21f7:f8b97f6c:e76ab2b4:7c6e18f8 name=3

# This file was auto-generated on Sun, 21 Dec 2014 08:07:40 +0000
# by mkconf $Id$

 

[Geeksmirage]

I have another thread where I got lots of responses. So if anyone else has this issue, please refer:
http://serverfault.com/questions/654012/mdadm-not-showing-raid5