Partitions: Amiga RDB partition on 2 TB disk way too big, while OK in AmigaOS 4.1

Hi Jens, hi Linux m68k developers,

I reported that as

https://bugzilla.kernel.org/show_bug.cgi?id=43511

I will attach there some more debug data like binary copy of RDB and such.

But maybe its easier to discuss here.

Sorry, forgot to keep Cc.

I think I will keep the disk as is for a while. I just won´t plug it to the Amiga, since I have my Amiga backup on another dedicated disk and do not want to overwrite my Linux backups. So its available for testing for a while. It should be save as long as I use the disk in Linux only.

For safety I will recreate all backups. I can checksum the BTRFS based backup partition for checksum errors, but fscking the other non BTRFS ones will only give a vague hint.

Am Sonntag, 17. Juni 2012 schrieb Martin Steigerwald:

Quoted 10 lines

Hi Jens, hi Linux m68k developers,

I reported that as

https://bugzilla.kernel.org/show_bug.cgi?id=43511

I will attach there some more debug data like binary copy of RDB and such.

But maybe its easier to discuss here.

I think this one is pretty serious:

merkaba:~> pvdisplay /dev/sdb1
--- Physical volume ---

   PV Name               /dev/sdb1
   VG Name               steigerwald
   PV Size               1,82 TiB / not usable 4,08 MiB
   Allocatable           yes
   PE Size               4,00 MiB
   Total PE              476931
   Free PE               105731
   Allocated PE          371200
   PV UUID               ZXMECC-JAir-lX8Q-rLhS-W1cS-quwz-b3FXWp

merkaba:~> vgdisplay steigerwald
--- Volume group ---
VG Name steigerwald
System ID

   Format                lvm2
   Metadata Areas        2
   Metadata Sequence No  7
   VG Access             read/write
   VG Status             resizable
   MAX LV                0
   Cur LV                5
   Open LV               1
   Max PV                0
   Cur PV                1
   Act PV                1
   VG Size               1,82 TiB
   PE Size               4,00 MiB
   Total PE              476931
   Alloc PE / Size       371200 / 1,42 TiB
   Free  PE / Size       105731 / 413,01 GiB
   VG UUID               uhjjE1-0yrD-Ch1A-d9qL-P5jY-UDXE-io4bpi

with

merkaba:~#1> amiga-fdisk -l /dev/sdc
Disk /dev/sdc: 3 heads, 16 sectors, 81396441 cylinders, RDB: 0 Logical Cylinders from 43 to 81396440, 24576 bytes/Cylinder

Device Boot Mount Begin End Size Pri BBlks System
/dev/sdc1 * 43 65536043 1572864024 0 0 Linux
native
/dev/sdc2 * 65536044 78643244 314572824 0 0
[unknown]
/dev/sdc3 * 78643245 81396440 66076704 0 0 Amiga
FFS Int.

Due to truncating oversized partition instead of refusing to use them the PV and consequently VG span the whole disk instead of leaving space for the >350GB in the two other partitions:

merkaba:~> cat /proc/partitions
major minor #blocks name

[…]

    8       16 1953514584 sdb
    8       17 1953513552 sdb1

(now sdb instead of sdc back when I run amiga-fdisk)

This is just asking for trouble. Thus:

Bug 43521 - Amiga RDB partitions: truncates miscaluted partitions size instead of refusing to use it
https://bugzilla.kernel.org/show_bug.cgi?id=43521

My suggestion is to bail out if a partition size looks insane and impossible.
Having to manually fix it up to access the data on disk still looks better to me than potentially overwriting lots of data.

Until today I never actually did an Amiga backup to the disk, I just created the two Amiga partitions and copied some screenshots of them but that might be enough to explain the checksum errors I found in a BTRFS backup partition.

I am now checking my Linux backups. They might be save, cause not all space on the volume group is used.

See:

kernel got struck while scrubbing BTRFS with node- and leafsize 32768
http://www.mail-archive.com/[email protected]/msg17108.html

s/struck/stuck

Thanks,

By the way, what did you use to setup the Amiga RDBs?