Dne 29.9.2017 v 18:42 Jan Tulak napsal(a):
Hi guys,
I found out this difference and I'm not sure what is the cause. A
command for creating a thin LV, which works on Archlinux, Centos and
Fedora, fails on Debian and Ubuntu:

lvm lvcreate FOOvg1 \
     -T \
     -l 100%PVS \
     -n FOOvg1_thin001 \
     /dev/loop0 /dev/loop1 /dev/loop2

Hi

This command is not actually creating 'thin'  - only a thin-pool.
For 'thin' you need to specify -V  --virtualsize.

The usage of -T is 'smart' flag - telling lvm2 to do 'something' thin/thin-pool oriented.

If you want to be 'exact' you can use --type thin or --type thin-pool giving you more errors and requiring user more specific option for passing in.


When it is created, lvs shows attributes "twi-a-tz--". But Debian and
Ubuntu complain that  "--name may only be given when creating a new
thin Logical volume or snapshot," even though the command states it
should be thin with -T. A script that tests this issue is at the end
of this email

Yep - the logic of command is internally enhanced over time and when user does specify parameters in a way where lvm2 can interpret them uniquely - it will do it.

BTW step-by around ;) for detailed explanation of all possible combination users can use to create thin-pool or thin or both volumes at the same time.

Do you know if there is a reason for this different behaviour?

It's not different - newer version is 'enhanced' and just accepts wider syntax range.

Versions seem to be close enough for it not to be a change in LVM

Hmm, close enough 111 and 171 ??


behaviour, so I suspect some downstream or configuration changes. All
tested distributions were run in their current stable versions, up to
date. For example:

The original naming convention with pool names was to add the name next to VG name.

lvcreate -T -L10 vg/pool

Pool is 'special' type of LV - thus it got this privileged naming and standard option --name was normally left for 'thin' when user specifies -V.

Newer version of lvm2 can use  --name with --size specifier for pool name
when there is no virtual size given as its unique combination.

Debian:
# cat /etc/debian_version
8.9
# lvm version
   LVM version:     2.02.111(2) (2014-09-01)
   Library version: 1.02.90 (2014-09-01) >    Driver version:  4.27.0

I'd suggest upgrading your Debian machine....

Regards

Zdenek

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