Questions tagged [device-mapper]

The device mapper is a block layer component which allows the creation of virtual block devices. LVM2 is based on it.

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3answers
3k views

Device mapper table alignment inconsistency

In the journal, I'm getting lines such as: Jan 27 18:23:08 tara kernel: device-mapper: table: 254:2: adding target device sdb2 caused an alignment inconsistency: physical_block_size=4096, ...
5
votes
1answer
2k views

What does `cryptsetup resize` do if LUKS doesn't store partition size?

The LUKS / dm-crypt / cryptsetup FAQ page says: 2.15 Can I resize a dm-crypt or LUKS partition? Yes, you can, as neither dm-crypt nor LUKS stores partition size. I'm befuzzled: What is "...
4
votes
1answer
335 views

dmsetup: Where is persistent metadata stored?

The dmsetup snapshot documentation says: <persistent?> is P (Persistent) or N (Not persistent - will not survive after reboot). O (Overflow) can be added as a persistent store option to allow ...
1
vote
1answer
470 views

device-mapper linear documentation parameters

Here is the documentation for using device-mapper linear: https://www.kernel.org/doc/Documentation/device-mapper/linear.txt I am trying to understand this documentation. It says it takes 2 parameters:...
0
votes
1answer
346 views

Can't create persistent snapshot device with `dmsetup`

I am trying to create a dmsetup snapshot device be able to rollback changes made by fsck. I think I'm calling dmsetup incorrectly. Here's an example: $ truncate -s 4096 real snapshot $...