Bug#717313: lvm2: Enable issue_discards = 1 automatically on non-rotational (SSD) disks?

Petter Reinholdtsen pere at hungry.com
Sun Aug 6 07:16:55 UTC 2017

[Laurent Bigonville]
> What I understand from this bug and Zdenek (who is apparently LVM2 upstream)
> message is that by default the discard requests are already passed to the
> underlying device during regular operation, this was definitely not really
> clear in my head, maybe this should be explained in the comments from the
> configuration file.

For the record, people still believe issue_discards=1 is needed in
LVM for SSD disks.  I just noticed 
<URL: http://blog.liw.fi/posts/2017/08/05/enabling_trim_discard_on_debian_ext4_luks_and_lvm/ >
suggesting to set it by default.  If it really is not needed nor wanted,
it should be documented somewhere in LVM close to where people setting in
SSD disks are looking.

A while back, I created a deb named ssd-setup to automatically set up Debian for
a SSD disk.  Until I understand more about the LVM issue, I automatically
enable issue_discards=1 in
<URL: https://anonscm.debian.org/cgit/collab-maint/ssd-setup.git >.  But
is this a bad idea or simply useless?

Happy hacking
Petter Reinholdtsen

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