On Thu, Oct 29, 2020 at 02:44:39PM +0100, Aleksander De wrote:
> Hi.
>
> Are there any downsides or potential issues which may happen when
> extending boundaries for OpenBSD partition on >2TB disk while using
> MBR for booting it at the same time? I need MBR otherwise the machine
> will not boot. BIOS/RAID controller does not support UEFI.
>
> Here you can see MBR with its 2TB limit:
> # fdisk sd0
> Disk: sd0 geometry: 267349/255/63 [4294961685 Sectors]
> Offset: 0 Signature: 0xAA55
> Starting Ending LBA Info:
> #: id C H S - C H S [ start: size ]
> -------------------------------------------------------------------------------
> 0: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> 1: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> 2: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
> *3: A6 0 4 5 - 267342 56 42 [ 256: 4294852544 ] OpenBSD
>
> In disklabel I have extended boundaries ('b' command') in order to be able to
> utilize whole disk - and use big encrypted partition 'e'. I have small
> root partition at the beginning in order to boot from it and access from
> remote via ssh + decrypt big partition manually, then start services.
>
> # disklabel sd0
> # /dev/rsd0c:
> type: SCSI
> disk: SCSI disk
> label: Block Device
> duid: 288724ae82038959
> flags:
> bytes/sector: 512
> sectors/track: 255
> tracks/cylinder: 511
> sectors/cylinder: 130305
> cylinders: 44967
> total sectors: 5859442688
> boundstart: 256
> boundend: 5859442688
> drivedata: 0
>
> 16 partitions:
> # size offset fstype [fsize bsize cpg]
> a: 14724192 256 4.2BSD 2048 16384 12960 # /
> b: 16809362 14724448 swap # none
> c: 5859442688 0 unused
> d: 14724192 31533824 4.2BSD 2048 16384 1
> e: 5813184640 46258048 RAID
>
> the same in more human-readable form:
> # disklabel -E sd0
> Label editor (enter '?' for help at any prompt)
> sd0> p g
> OpenBSD area: 256-5859442688; size: 2794.0G; free: 0.0G
> # size offset fstype [fsize bsize cpg]
> a: 7.0G 256 4.2BSD 2048 16384 12960 # /
> b: 8.0G 14724448 swap # none
> c: 2794.0G 0 unused
> d: 7.0G 31533824 4.2BSD 2048 16384 1
> e: 2771.9G 46258048 RAID
>
> I don't need whole 3TB now, just feel better knowing that I can use it safe.
> If it may cause some issues I can keep 2TB limit to OpenBSD partition.
> --
> Aleksander
>
I know of no issue doing that, you should be fine.
-Otto
