raid1 bitmap=internal fails for specific sizes

raid1 bitmap=internal fails for specific sizes

[Markus Hochholdinger]

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Hello,

i've hit a weird problem with creating raid1 bitmaps. Setting a internal 
bitmap while creating a raid1 
(mdadm --create /dev/mdX --level=1 --raid-disks=2 --bitmap=internal /dev/vg0/a /dev/vg0/b) 
or growing a raid1 with a internal bitmap 
(mdadm --grow /dev/mdX --bitmap=internal) i a got a failure for specific 
device sizes of /dev/vg0/a and /dev/vg0/b.

The sizes i get errors are 7680MB, 15GB, 30GB, 60GB, 120GB and 240GB. I get no 
errors with 10GB, 16GB, 17GB, 20GB, 25GB, 29GB, 31GB, 38GB, 40GB, 50GB, 59GB, 
70GB, 75GB and 90GB.

It doesn't matter if i set the bitmap while creating the raid1 or after the 
raid1 is created and synced.

I'm using Debian lenny with mdadm 2.6.7 (2.6.7.1-1) and the problem occurs 
with kernel 2.6.26-1-xen-amd64 and also with kernel 2.6.18 from xensource.

The mdadm message is (while create):
  mdadm: RUN_ARRAY failed: Input/output error
  mdadm: stopped /dev/md9
The kernel message is:
  md: bind<dm-1>
  md: bind<dm-2>
  md: md9: raid array is not clean -- starting background reconstruction
  raid1: raid set md9 active with 2 out of 2 mirrors
  md9: bitmap file is out of date (0 < 1) -- forcing full recovery
  md9: bitmap file is out of date, doing full recovery
  attempt to access beyond end of device
  dm-2: rw=16, want=31457288, limit=31457280
  attempt to access beyond end of device
  dm-1: rw=16, want=31457288, limit=31457280
  md9: bitmap initialized from disk: read 15/16 pages, set 489472 bits, 
status: -5
  md9: failed to create bitmap (-5)
  md: pers->run() failed ...
  md: md9 stopped.
  md: unbind<dm-2>
  md: export_rdev(dm-2)
  md: unbind<dm-1>
  md: export_rdev(dm-1)

Perhaps the important message is "dm-2: rw=16, want=31457288, limit=31457280" 
which i think is some sort of rounding error?

Is this some known bug or perhaps is this bug allready fixed (i didn't find 
anything similar on this list)?

For now i'll avoid these sizes for raid1.


-- 
greetings

eMHa

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