[Important Notice] Changes the type of services to better integrate with systemd for LeoFS 1.4

[yoshiyuki kanno]

Dear LeoFS users,

Next LeoFS upcoming release 1.4.0 is around the corner and will come
along with many exciting features (however it's out of scope of this
mail) and lots of improvements.

One of the important improvements is as the subject says, changes the
type of services for systemd from "basic" type to "notify" type.
This change would give the advantage of systemd actually knowing when
the node has finished starting up ("systemctl start
leofs-manager-master" won't return until master has actually started),
which allows correct dependencies between nodes on the same system and
better control/status of the nodes.

There should be no extra steps required to upgrade to 1.4 from 1.3.8
with systemd services already running (not to mention it's also
possible to upgrade to 1.4 from any of 1.3.x. for more details, please
refer http://leo-project.net/leofs/docs/admin/system_operations/systemd/
if you'd want to run LeoFS under systemd) however there might be some
special cases that we've missed which will cause some problem and at
worst service(s) will be killed & restarted over and over again
without any notification to users.

So we'd strongly recommend any of you who have a LeoFS cluster with
systemd running to try upgrading processes with the release candidates
on your dev (and/or staging) environment before getting the production
cluster upgraded to 1.4.0.
The latest release candidate has been released yesterday on
https://github.com/leo-project/leofs/releases/tag/1.4.0-rc3 so if
that's is the case then please try it out.

Feel free to contact us if you face any problems.

Best Regards,

--
Yoshiyuki Kanno
LeoFS Committer(http://leo-project.net/leofs/index.html)