Re: Kernel 2.6.17 and RAID5 Grow Problem (critical section backup)

[Justin Piszcz <jpiszcz@lucidpixels.com>]

On Fri, 7 Jul 2006, Justin Piszcz wrote:

> p34:~# mdadm /dev/md3 -a /dev/hde1
> mdadm: added /dev/hde1
>
> p34:~# mdadm -D /dev/md3
> /dev/md3:
>        Version : 00.90.03
>  Creation Time : Fri Jun 30 09:17:12 2006
>     Raid Level : raid5
>     Array Size : 1953543680 (1863.04 GiB 2000.43 GB)
>    Device Size : 390708736 (372.61 GiB 400.09 GB)
>   Raid Devices : 6
>  Total Devices : 7
> Preferred Minor : 3
>    Persistence : Superblock is persistent
>
>    Update Time : Fri Jul  7 08:25:44 2006
>          State : clean
> Active Devices : 6
> Working Devices : 7
> Failed Devices : 0
>  Spare Devices : 1
>
>         Layout : left-symmetric
>     Chunk Size : 512K
>
>           UUID : e76e403c:7811eb65:73be2f3b:0c2fc2ce
>         Events : 0.232940
>
>    Number   Major   Minor   RaidDevice State
>       0      22        1        0      active sync   /dev/hdc1
>       1      56        1        1      active sync   /dev/hdi1
>       2       3        1        2      active sync   /dev/hda1
>       3       8       49        3      active sync   /dev/sdd1
>       4      88        1        4      active sync   /dev/hdm1
>       5       8       33        5      active sync   /dev/sdc1
>
>       6      33        1        -      spare   /dev/hde1
> p34:~# mdadm --grow /dev/md3 --raid-disks=7
> mdadm: Need to backup 15360K of critical section..
> mdadm: Cannot set device size/shape for /dev/md3: No space left on device
> p34:~# mdadm --grow /dev/md3 --bitmap=internal --raid-disks=7
> mdadm: can change at most one of size, raiddisks, bitmap, and layout
> p34:~# umount /dev/md3
> p34:~# mdadm --grow /dev/md3 --raid-disks=7
> mdadm: Need to backup 15360K of critical section..
> mdadm: Cannot set device size/shape for /dev/md3: No space left on device
> p34:~#
>
> The disk only has about 350GB of 1.8TB used, any idea why I get this error?
>
> I searched google but could not find anything on this issue when trying to 
> grow the array?
>
>
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Is it because I use a 512kb chunksize?

Jul  7 08:44:59 p34 kernel: [4295845.933000] raid5: reshape: not enough 
stripes.  Needed 512
Jul  7 08:44:59 p34 kernel: [4295845.962000] md: couldn't update array 
info. -28

So the RAID5 reshape only works if you use a 128kb or smaller chunk size?

Justin.