lvmteam/lvm2

Custom `segtypes`

Closed this issue · 1 comments

Wesselinator commented

Weird question but is it at all possible to introduce custom segtypes into lvm without modifying the code?

The reason I am asking is because it seems that QNAP uses a strange tier-thin-pool segtype.
LVM installed on a different system can't do anything without erroring with:

WARNING: unrecognized segment type tier-thin-pool

From some googling it doesn't look like there are any seprate packages I can install to read that.

Just wondering if there is some mechanism I am missing (like a module or something) that you can use to add other segtypes.

If it helps,
Version of LVM on external system

  LVM version:     2.03.17(2) (2022-11-10)
  Library version: 1.02.187 (2022-11-10)

Version of LVM on QNAP

  LVM version:     2.02.138(2)-git (2015-12-14)
  Library version: 1.02.144-git (2015-12-14)
Wesselinator commented

Googled a little harder.

Found their GPL artefacts here

The answer to my own question is yes(?)
I inspected their code and they are adding the special segtype

lib/metadata/segtype.h

#define SEG_TYPE_NAME_THICK		"thick"
#define SEG_TYPE_NAME_THIN_POOL		"thin-pool"
#define SEG_TYPE_NAME_TIER_THIN_POOL	"tier-thin-pool"
#define SEG_TYPE_NAME_CACHE		"cache"
#define SEG_TYPE_NAME_CACHE_POOL	"cache-pool"