Problems with raid5

[samrise]

I noticed that i had the wrong partition type, but even after correct it the error is the same:

Code: Select all

Command (m for help): p

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks  Id System
/dev/sda1               9          72      514080  83 Linux
/dev/sda2              73         136      514080  83 Linux
/dev/sda3             137         200      514080  82 Linux swap
/dev/sda4             201      121601   975153532+  5 Extended
/dev/sda5             209         312      835380  83 Linux
/dev/sda6             321         328       64260  83 Linux
/dev/sda7             337         400      514080  83 Linux
/dev/sda8             409      121600   973474740  fd Linux raid autodetect

Command (m for help): q

root@nas:/ # mdadm --manage /dev/md0 --add /dev/sda8
mdadm: add new device failed for /dev/sda8 as 4: Invalid argument


[Jocko]

Hi samrise,

Sorry but it was the expected behaviour and that confirms you can not include in a same raid ms-dos and gpt table.

Now, you need to backup your data on sda8. (If your data size on md0 is too big to store in sda8, you need to use an USB disk).
So,
- Select again as fs type 83 on sda8, and reboot the nas. Vol-A should exist again
- if md0 is the addons volume, select Vol-A as it with the option "Move the technical share" in the main setup menu
- After if there are other shares set on md0 (should be volume RD5-0), move them by using the move feature of the edit share menu.

Then check if all shares are on Vol-A (see shares table)
-Now you can destroy md0 by following the tutorial for RAID5 but do not reboot the NAS
-Use gdisk to destroy your gpt table on sd[bcde]
-Use fdisk to build the new ms-dos table by following this Howto http://plugout.net/download/file.php?id=3823(we forgot to include it in the topic for fvdw-sl console 5.5)
-Reboot the nas, you should have now 5 volumes (Vol-A, Vol-B,...Vol-E)
-Build the new raid by following the Chapter II of this tutorials

Note: all these steps require time

[samrise]

I dont have enough space available elsewhere to move data currently on raid. I guess we have to postpone probably a few weeeks.

[Jocko]

Ok
So wait.

[samrise]

Btw, this current setup that i have gave some ideas. If i keep sda with msdos can i use bigger disks with gtp partitions? Sure, i loose one slot but that way i could use disks bigger than 2tb.

[Jocko]

Yes only sda must have a ms-dos table and then you can use bigger disks using gpt table in you raid as long as you don't include sda in the raid device.

Note: the cost of a raid5 built with 4 disks is 25% (and 33% if it contains only 3 disks)

[samrise]

Indeed, the cost its something to considerer. I'm just thinking ahead, since its not a problem at the moment since i have 5 1TB disks.

As soon as i free some space i will move data out of the raid and we can try to add sda.

[samrise]

Ok, something weird happened.

Today i changed back /dev/sda8 to 83 and after reboot i noticed it was not mounted. I went to the web-admin and it shows sda8 as part of raid. Can you help me to check whats happening?

root@nas:/ # cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md0 : active raid5 sdb8[0] sde8[3] sdd8[2] sdc8[1]
2921581440 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>
root@nas:/ # mdadm --detail /dev/md0
/dev/md0:
Version : 00.90.03
Creation Time : Tue Aug 18 01:51:37 2015
Raid Level : raid5
Array Size : 2921581440 (2786.24 GiB 2991.70 GB)
Device Size : 973860480 (928.75 GiB 997.23 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Sun Oct 4 20:50:24 2015
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 64K

UUID : fb3aeaaa:c4db9f4e:5b39e2ab:7241a439
Events : 0.1692

Number Major Minor RaidDevice State
0 8 56 0 active sync /dev/sdb8
1 8 40 1 active sync /dev/sdc8
2 8 24 2 active sync /dev/sdd8
3 8 8 3 active sync /dev/sde8
root@nas:/ # mdadm --examine /dev/sda8
/dev/sda8:
Magic : a92b4efc
Version : 00.90.00
UUID : fb3aeaaa:c4db9f4e:5b39e2ab:7241a439
Creation Time : Tue Aug 18 01:51:37 2015
Raid Level : raid5
Device Size : 973860480 (928.75 GiB 997.23 GB)
Array Size : 2921581440 (2786.24 GiB 2991.70 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0

Update Time : Sun Oct 4 01:19:04 2015
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : 1cad4f83 - correct
Events : 0.1692

Layout : left-symmetric
Chunk Size : 64K

Number Major Minor RaidDevice State
this 4 8 72 -1 spare /dev/sda8

0 0 8 56 0 active sync /dev/sdb8
1 1 8 40 1 active sync /dev/sdc8
2 2 8 24 2 active sync /dev/sdd8
3 3 8 8 3 active sync /dev/sde8

[Jocko]

That means that even if mdadm failed to include sda8 in the raid at least it wrote the raid superblock.

So you need to erase it by the command

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mdadm --zero-superblock /dev/sda8

reboot the NAS and sda8 should be mounted on /share/1000

[samrise]

Indeed, that was the problem. Its fixed now. Thank you.