Re: mdadm: Insufficient head-space for reshape on /dev/sda2

[Wols Lists <antlists@youngman.org.uk>]

Given that no-one else has chimed in ...

Am I right in guessing that this particular array is quite old? 500MB is
very small nowadays ...

It also seems weird that you have a raid-10 with 2 drives and 2 spares ...

I would guess that, because the amount of space required by mdadm has
grown over the years, when you created the array years ago you used all
available space and now there's not enough for the metadata that mdadm
requires nowadays.

What are you trying to achieve, because the current setup does not make
sense without some explanation, and I guess you're better off migrating
to larger hard disks ...

Cheers,
Wol

On 04/08/20 12:18, H. Morala (HyD) wrote:
> Hello,
> 
> We tried to do:
> 
> 	mdadm --grow /dev/md126 --raid-devices=4 
> 
> and we get:
> 
> 	mdadm: Insufficient head-space for reshape on /dev/sda2
> 
> 
> This is the present  configuration:
> 
> # mdadm --misc --detail /dev/md126
> /dev/md126:
>           Version : 1.0
>     Creation Time : Fri May 27 12:40:54 2016
>        Raid Level : raid10
>        Array Size : 512960 (500.94 MiB 525.27 MB)
>     Used Dev Size : 512960 (500.94 MiB 525.27 MB)
>      Raid Devices : 2
>     Total Devices : 4
>       Persistence : Superblock is persistent
> 
>       Update Time : Mon Aug  3 17:33:04 2020
>             State : clean 
>    Active Devices : 2
>   Working Devices : 4
>    Failed Devices : 0
>     Spare Devices : 2
> 
>            Layout : near=2
>        Chunk Size : 64K
> 
> Consistency Policy : resync
> 
>              Name : boot
>              UUID : 5fc23b3c:93ecd502:0fbf3b82:adc7ad2d
>            Events : 746
> 
>    Number   Major   Minor   RaidDevice State
>       0       8        2        0      active sync set-A   /dev/sda2
>       4       8       50        1      active sync set-B   /dev/sdd2
> 
>       2       8       18        -      spare   /dev/sdb2
>       3       8       34        -      spare   /dev/sdc2
> 
> 
> 
> # cat /etc/mdadm.conf 
> ARRAY /dev/md/boot_0 metadata=1.0 spares=2 name=boot UUID=5fc23b3c:93ecd502:0fbf3b82:adc7ad2d
> 
> # cat /proc/mdstat 
> Personalities : [raid1] [raid10] [raid0] 
> md126 : active raid10 sdd2[4] sdc2[3](S) sdb2[2](S) sda2[0]
>      512960 blocks super 1.0 2 near-copies [2/2] [UU]
> 
> # fdisk /dev/sda
> 
> The device presents a logical sector size that is smaller than
> the physical sector size. Aligning to a physical sector (or optimal
> I/O) size boundary is recommended, or performance may be impacted.
> Welcome to fdisk (util-linux 2.23.2).
> 
> Changes will remain in memory only, until you decide to write them.
> Be careful before using the write command.
> 
> 
> Orden (m para obtener ayuda): p
> 
> Disk /dev/sda: 500.1 GB, 500107862016 bytes, 976773168 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
> Disk label type: dos
> Identificador del disco: 0x0005ff1f
> 
> Disposit. Inicio    Comienzo      Fin      Bloques  Id  Sistema
> /dev/sda1            2048     8265727     4131840   8e  Linux LVM
> /dev/sda2   *     8265728     9291775      513024   fd  Linux raid autodetect
> /dev/sda3         9291776   974243839   482476032   fd  Linux raid autodetect
> 
> 
> # parted /dev/sda
> GNU Parted 3.1
> Usando /dev/sda
> Welcome to GNU Parted! Type 'help' to view a list of commands.
> (parted) print free
> Model: ATA Crucial_CT500MX2 (scsi)
> Disk /dev/sda: 500GB
> Sector size (logical/physical): 512B/4096B
> Partition Table: msdos
> Disk Flags: 
> 
> Numero  Inicio  Fin     Tamaño  Typo     Sistema de ficheros  Banderas
>        32,3kB  1049kB  1016kB           Free Space
> 1      1049kB  4232MB  4231MB  primary                       lvm
> 2      4232MB  4757MB  525MB   primary  xfs                  arranque, raid
> 3      4757MB  499GB   494GB   primary                       raid
>        499GB   500GB   1295MB           Free Space
>