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

[Petter Reinholdtsen]

Package: lvm2
Version: 2.02.95-7
Severity: wishlist

Hi.

According to several recipes on how to set up Linux on a SSD disk, LVM
need to be reconfigured to issue discard (aka TRIM) instructions to the
underlying storage device.  This is done by modifying /etc/lvm/lvm.conf
and setting issue_discards = 1 in the devices section.

Why not set the option automatically when the underlying device is not
rotational?  In my case, the LVM physical device is /dev/dm-0 (encrypted
device), and /sys/block/dm-0/queue/rotational return 0.  If LVM used the
rotational value to decide to set the issue_discard option, there would
be no need for manual configuration with LVM and SSD disks.

Is there some reason this isn't done already, except lack of time to
implement it?

-- 
Happy hacking
Petter Reinholdtsen