[linux-lvm] Questions about issue_discards

[CJ Kucera]

Hello, list!

I've started to play around with SSD drives and was curious about a
couple aspects of the issue_discards configuration option.

1) The lvm.conf comments note that when enabled, it'll still only
(obviously) issue discards to storage which happens to support it.  Is
there a way of querying block devices to find out if they support the
feature?

2) Would a change to the issue_discards parameter be picked up
automatically by the running kernel?  The lvm.conf manpage mentions that
it remembers the timestamp of the file "between commands" and will apply
changes then, but it almost sounds like that'd be mostly for things like
the device scanning list, etc.

Thanks!

-CJ