Regarding influence LVM without "0x8e" partition type

[Minoru Asano]

Hello,

[ENVIRONMENT]
RHEL ES4 update3 or update4

[SITUATION]
I know that usually we must set "0x8e" as partition type by using fdisk command
when we create LVM file system at first.

But one customer does not set "0x8e" as partition type, and it is "unknown" type, and
he could create LVM file system.
Now the file system works with no problem.

[QUESTION]
- Is there possibility to occur any trouble in this situation ?
Or is there any restriction ?
For example, he can not expand LVM file system, so on.

- Is there possibility to occur any trouble in the future ?
For example, the partition type information is used with any file system operation due to
new implementation, so on.

Thank you for support and advice.
Best Regards.
/Minoru.Asano

[Matti_Kurkela · Accepted solution]

For Linux, the partition type is mostly "information only". If you know what the partition really contains, you can ignore the partition type. If you're running only Linux on that system, won't transfer partitioned disks to other systems, and use a boot loader that installs into MBR or otherwise does not care about partition types, then the partition type is practically meaningless.

The "vgscan" command looks for a LVM signature in a known location on each partition. It ignores the partition type, as you noticed.

If that disk is accessed using some other operating system, the disk management tools of that system might become confused and/or treat the partition as unused and "helpfully" format it for you. This might cause data loss.

On the other hand, partition type 0xfd has/used to have some meaning for Linux. It indicates a software RAID partition. Any detected RAID partitions with type 0xfd will be automatically activated when the kernel is starting up. This makes it possible to build a system without initrd and still allow your root filesystem be on a software RAID device. However, this is not usually very important because most distributions use initrd by default.

MK

[Stuart Browne]

LVM can either use partitions, or whole-devices for their physical-extents.

If the whole-device is being used for LVM, then there will be no partitions on it.

Is this the case on this system?

[Minoru Asano]

Hello,

Thank you for reply.

>Is this the case on this system?

The customer said that he use RAID disk
for LSM disk, so it might be whole-device.

For now I have explained that there is no
influence for LSM file system.

Thank you.
Best Regards.
/Minoru.Asano