Re: No md superblock immediately after creating RAID 5 /dev/md0

3 messages, 2 authors, 2008-09-16 · open the first message on its own page

Re: No md superblock immediately after creating RAID 5 /dev/md0

From: <hidden>
Date: 2008-08-29 05:47:50 

Hi Neil,

Sorry for the confusion. I mistyped the -C command in my initial email 
(forgot the hot-spare) and thus the confusion.

Here is the full output from the top using copy/paste. Thank you in 
advance for your help!!


root@localhost:~# fdisk -l

Disk /dev/sda: 2095 MB, 2095865856 bytes
65 heads, 62 sectors/track, 1015 cylinders
Units = cylinders of 4030 * 512 = 2063360 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1         500     1007469   83  Linux
/dev/sda2   *         501        1015     1037725   83  Linux

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0b65bb81

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x273d0b7e

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdd: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x03cf614e

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sde: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xa6b886bb

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdf: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x65752a1a

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdg: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x9f188135

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdh: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xc19605d4

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdi: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x1e6c4f8e

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdj: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xd13edb81

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdk: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x5bbd83b9

Disk /dev/sdk doesn't contain a valid partition table

Disk /dev/sdl: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xebcdc998

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdm: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xd90b43ff

   Device Boot      Start         End      Blocks   Id  System
root@localhost:~#
root@localhost:~# cat /etc/mdadm.conf
root@localhost:~#
root@localhost:~# mdadm --examine --scan --verbose
root@localhost:~#
root@localhost:~# mdadm -Cv /dev/md0 -n11 -l5 -c128 /dev/sd[b-l] -x1 
/dev/sdm -R -f --verbose
mdadm: layout defaults to left-symmetric
mdadm: size set to 976762496K
mdadm: array /dev/md0 started.
root@localhost:~#
root@localhost:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
md0 : active raid5 sdm[11](S) sdl[10] sdk[9] sdj[8] sdi[7] sdh[6] 
sdg[5] sdf[4] sde[3] sdd[2] sdc[1] sdb[0]
       9767624960 blocks level 5, 128k chunk, algorithm 2 [11/11] 
[UUUUUUUUUUU]
       [>....................]  resync =  0.0% (265128/976762496) 
finish=306.8min speed=53025K/sec

unused devices: <none>
root@localhost:~#
root@localhost:~# cat /etc/mdadm.conf
root@localhost:~#
root@localhost:~# mdadm --examine --scan --verbose
ARRAY /dev/md0 level=raid5 num-devices=11 
UUID=09db8873:25545721:e5d66b81:63573add
    spares=1   
devices=/dev/sdm,/dev/sdl,/dev/sdk,/dev/sdj,/dev/sdi,/dev/sdh,/dev/sdg,/d
ev/sdf,/dev/sde,/dev/sdd,/dev/sdc,/dev/sdb
root@localhost:~#
root@localhost:~# mdadm -D /dev/md0
/dev/md0:
        Version : 00.90
  Creation Time : Fri Aug 29 05:34:40 2008
     Raid Level : raid5
     Array Size : 9767624960 (9315.13 GiB 10002.05 GB)
  Used Dev Size : 976762496 (931.51 GiB 1000.20 GB)
   Raid Devices : 11
  Total Devices : 12
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Fri Aug 29 05:34:41 2008
          State : active, resyncing
 Active Devices : 11
Working Devices : 12
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 128K

 Rebuild Status : 0% complete

           UUID : 09db8873:25545721:e5d66b81:63573add
         Events : 0.3

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       2       8       48        2      active sync   /dev/sdd
       3       8       64        3      active sync   /dev/sde
       4       8       80        4      active sync   /dev/sdf
       5       8       96        5      active sync   /dev/sdg
       6       8      112        6      active sync   /dev/sdh
       7       8      128        7      active sync   /dev/sdi
       8       8      144        8      active sync   /dev/sdj
       9       8      160        9      active sync   /dev/sdk
      10       8      176       10      active sync   /dev/sdl

      11       8      192        -      spare   /dev/sdm
root@localhost:~#
root@localhost:~# shutdown -r now

Broadcast message from root@localhost
        (/dev/pts/0) at 5:35 ...

The system is going down for reboot NOW!
root@localhost:~# login as: root
root@192.168.1.15's password:
root@localhost:~#
root@localhost:~#
root@localhost:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
unused devices: <none>
root@localhost:~#
root@localhost:~# mdadm --examine --scan --verbose
ARRAY /dev/md0 level=raid5 num-devices=11 
UUID=09db8873:25545721:e5d66b81:63573add
    spares=1   
devices=/dev/sdm,/dev/sdl,/dev/sdk,/dev/sdj,/dev/sdi,/dev/sdh,/dev/sdg,/d
ev/sdf,/dev/sde,/dev/sdd,/dev/sdc,/dev/sdb
root@localhost:~#
root@localhost:~# cat /etc/mdadm.conf
root@localhost:~#
root@localhost:~# mdadm --assemble --scan --verbose
mdadm: No arrays found in config file
root@localhost:~#
root@localhost:~# mdadm --scan
mdadm: --scan does not set the mode, and so cannot be the first option.
root@localhost:~# mdadm -E /dev/md0
mdadm: cannot open /dev/md0: No such file or directory
root@localhost:~#
root@localhost:~# mdadm -X /dev/md0
mdadm: failed to find file /dev/md0: No such file or directory
root@localhost:~# mdadm --assemble --scan --verbose /dev/md0
mdadm: /dev/md0 not identified in config file.
root@localhost:~# mdadm --query /dev/md0
mdadm: cannot open /dev/md0: No such file or directory
root@localhost:~#





-----Original Message-----
From: NeilBrown <redacted>
To: thomas62186218@aol.com
Sent: Thu, 28 Aug 2008 5:04 am
Subject: Re: No md superblock immediately after creating RAID 5 /dev/md0










On Thu, August 28, 2008 6:32 pm, thomas62186218@aol.com wrote:

mdadm -Cv /dev/md0 -n12 -l5 -c128 /dev/sd[b-m] -R -f
                       ^^
12.



root@localhost:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
[raid4] [ra           id10]
md0 : active raid5 sdm1[11](S) sdl1[10] sdk1[9] sdj1[8] sdi1[7] 
sdh1[6]
sdg1[5]            sdf1[4] sde1[3] sdd1[2] sdc1[1] sdb1[0]
       4883839360 blocks level 5, 16k chunk, algorithm 2 [11/11]
                                                            ^^
11!


root@localhost:~# cat /etc/mdadm.conf
DEVICE  /dev/sd*
ARRAY /dev/md0 level=raid5 num-devices=12
                                         ^^
12 ??


   Raid Devices : 11
                    ^^

Something odd here.


root@localhost:/var/log# mdadm --assemble --scan
mdadm: no devices found for /dev/md0
Could you add --verbose to that line and try again?

NeilBrown

P.S.  Thanks for including lots of details!

Re: No md superblock immediately after creating RAID 5 /dev/md0

From: NeilBrown <hidden>
Date: 2008-08-29 06:01:23 

On Fri, August 29, 2008 3:47 pm, thomas62186218@aol.com wrote:
Hi Neil,

Sorry for the confusion. I mistyped the -C command in my initial email
(forgot the hot-spare) and thus the confusion.

Here is the full output from the top using copy/paste. Thank you in
advance for your help!!
In the first mail you sent, there was an mdadm.conf.
But now:


root@localhost:~# cat /etc/mdadm.conf
root@localhost:~#
there isn't.
Why is that?

If you want mdadm to assemble an array you need to tell it where to find
the devices and how to recognise them.  The mdadm.conf you had before
was exactly the right sort of thing to have.
Without it you need to be more explicit
  mdadm -A /dev/md0 /dev/sd[b-m]
maybe.
Or after creating the array
  mdadm -D > /etc/mdadm.conf

NeilBrown

Re: No md superblock immediately after creating RAID 5 /dev/md0

From: <hidden>
Date: 2008-09-16 09:37:50 

Hi Neil,

Thank you for your help on this. It seems like running mdadm -D > 
/etc/mdadm.conf is the way to go.

But, this raises another question. In EVMS, you do not need to ever 
tell it how to assemble an array. In fact, we could have a EVMS RAID of 
3 drives, pull the 3 drives out, and put them into a brand new system 
with no configuration files, etc. and EVMS would instantly recognize 
the RAID device, and even all volumes on it.

With mdadm, though, it seems like without /etc/mdadm.conf (or manually 
telling mdadm what to assemble), mdadm cannot really tell on its own 
what to do. This puts greater importance of course on /etc/mdadm.conf.

Is there any way around this? In other words, is there a way to 
auto-assemble arrays without using mdadm -A or without having 
/etc/mdadm.conf?

Finally, if /etc/mdadm.conf is the solution, can you advise what should 
happen when an md device is deleted? Should the "legacy" entries be 
left in /etc/mdadm.conf? Or should these be cleaned out? Any easy way 
to do this?

Thank you in advance for your help!

With Regards,
-Thomas


-----Original Message-----
From: NeilBrown <redacted>
To: thomas62186218@aol.com
Cc: linux-raid@vger.kernel.org
Sent: Thu, 28 Aug 2008 11:01 pm
Subject: Re: No md superblock immediately after creating RAID 5 /dev/md0










On Fri, August 29, 2008 3:47 pm, thomas62186218@aol.com wrote:
Hi Neil,

Sorry for the confusion. I mistyped the -C command in my initial email
(forgot the hot-spare) and thus the confusion.

Here is the full output from the top using copy/paste. Thank you in
advance for your help!!
In the first mail you sent, there was an mdadm.conf.
But now:


root@localhost:~# cat /etc/mdadm.conf
root@localhost:~#
there isn't.
Why is that?

If you want mdadm to assemble an array you need to tell it where to find
the devices and how to recognise them.  The mdadm.conf you had before
was exactly the right sort of thing to have.
Without it you need to be more explicit
  mdadm -A /dev/md0 /dev/sd[b-m]
maybe.
Or after creating the array
  mdadm -D > /etc/mdadm.conf

NeilBrown
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