issue with internal bitmaps

issue with internal bitmaps

[Luca Berra]

hello, i just realized that internal bitmaps do not seem to work
anymore.

kernel 2.6.17
mdadm 2.5.2

[root@localhost ~]# mdadm --create --level=1 -n 2 -e 1 --bitmap=internal /dev/md100 /dev/sda1 /dev/sda2
mdadm: array /dev/md100 started.

... wait awhile ...

[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md100 : active raid1 sda2[1] sda1[0]
      1000424 blocks super 1.0 [2/2] [UU]
      bitmap: 4/4 pages [16KB], 128KB chunk

unused devices: <none>
[root@localhost ~]# mdadm -X /dev/md100
        Filename : /dev/md100
           Magic : 00000000
mdadm: invalid bitmap magic 0x0, the bitmap file appears to be corrupted
         Version : 0
mdadm: unknown bitmap version 0, either the bitmap file is corrupted or you need to upgrade your tools

[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md100 : active raid1 sda2[1] sda1[0]
      1000424 blocks super 1.0 [2/2] [UU]
      bitmap: 0/4 pages [0KB], 128KB chunk

unused devices: <none>

[root@localhost ~]# mdadm -D /dev/md100
/dev/md100:
        Version : 01.00.03
  Creation Time : Thu Jul  6 16:05:10 2006
     Raid Level : raid1
     Array Size : 1000424 (977.14 MiB 1024.43 MB)
    Device Size : 1000424 (977.14 MiB 1024.43 MB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 100
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Thu Jul  6 16:07:11 2006
          State : active
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : 100
           UUID : 60cd0dcb:fde52377:699453f7:da96b9d4
         Events : 1

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8        2        1      active sync   /dev/sda2



-- 
Luca Berra -- bluca@comedia.it
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Re: issue with internal bitmaps

[Neil Brown]

On Thursday July 6, bluca@comedia.it wrote:
> hello, i just realized that internal bitmaps do not seem to work
> anymore.

I cannot imagine why.  Nothing you have listed show anything wrong
with md...

Maybe you were expecting
   mdadm -X /dev/md100
to do something useful.  Like -E, -X must be applied to a component
device.  Try
   mdadm -X /dev/sda1

Patch to documentation are always welcome :-)

NeilBrown

Re: issue with internal bitmaps

[Luca Berra]

On Fri, Jul 07, 2006 at 08:16:18AM +1000, Neil Brown wrote:
>On Thursday July 6, bluca@comedia.it wrote:
>> hello, i just realized that internal bitmaps do not seem to work
>> anymore.
>
>I cannot imagine why.  Nothing you have listed show anything wrong
>with md...
>
>Maybe you were expecting
>   mdadm -X /dev/md100
>to do something useful.  Like -E, -X must be applied to a component
>device.  Try
>   mdadm -X /dev/sda1
>
/me needs some strong coffe. yes you are right, sorry

L.


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Luca Berra -- bluca@comedia.it
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Re: issue with internal bitmaps

[Bill Davidsen]

Neil Brown wrote:

>On Thursday July 6, bluca@comedia.it wrote:
>  
>
>>hello, i just realized that internal bitmaps do not seem to work
>>anymore.
>>    
>>
>
>I cannot imagine why.  Nothing you have listed show anything wrong
>with md...
>
>Maybe you were expecting
>   mdadm -X /dev/md100
>to do something useful.  Like -E, -X must be applied to a component
>device.  Try
>   mdadm -X /dev/sda1
>
To take this from the other end, why should -X apply to a component? 
Since the components can and do change names, and you frequently mention 
assembly by UUID, why aren't the component names determined from the 
invariant array name when mdadm wants them, instead of having a user or 
script check the array to get the components?

Between udev and dynamic reconfiguration when component names have 
become less and less relevant, perhaps they can be less used in the future.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

Re: issue with internal bitmaps

[Bill Davidsen]

Bill Davidsen wrote:

> Neil Brown wrote:
>
>> On Thursday July 6, bluca@comedia.it wrote:
>>  
>>
>>> hello, i just realized that internal bitmaps do not seem to work
>>> anymore.
>>>   
>>
>>
>> I cannot imagine why.  Nothing you have listed show anything wrong
>> with md...
>>
>> Maybe you were expecting
>>   mdadm -X /dev/md100
>> to do something useful.  Like -E, -X must be applied to a component
>> device.  Try
>>   mdadm -X /dev/sda1
>>
> To take this from the other end, why should -X apply to a component? 
> Since the components can and do change names, and you frequently 
> mention assembly by UUID, why aren't the component names determined 
> from the invariant array name when mdadm wants them, instead of having 
> a user or script check the array to get the components?

Boy, I didn't say that well... what I meant to suggest is that when -E 
or -X are applied to the array as a whole, would it not be useful to 
itterate them over all of the components rather than than looking for 
non-existant data in the array itself?

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

Re: issue with internal bitmaps

[Luca Berra]

On Tue, Jul 18, 2006 at 09:34:35AM -0400, Bill Davidsen wrote:
>Boy, I didn't say that well... what I meant to suggest is that when -E 
>or -X are applied to the array as a whole, would it not be useful to 
>itterate them over all of the components rather than than looking for 
>non-existant data in the array itself?
the question i believe is to distinguish the case where an md device is
a component of another md device...
L.

-- 
Luca Berra -- bluca@comedia.it
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