RE: additional feature for monit-3.0 (for clusters)

[Jan-Henrik Haukeland]

> Agree - some suggestions?

A though one, a new name :-) If we do not find a good name (I'm blank), we
could combine, that is, use automonitor and autostart and set the value
properly in the parser, i.e. override the value of autostart if it's true. (and
document this behavior)

BTW, using monit together with heartbeat is interesting, do you think you could
write a FAQ or man file entry for this Oliver? (When we figure out what the
statement should be)

Jan-Henrik

> Oliver Jehle wrote:
>
> >No problems by inserting a new config statement...
> >
> >but it should be a xor with autostart... you cannot have autostart=true and
> >monitor only manual started :
> >
> >so i think, giving the autostart a better name would be easier !!!
> >
> >
> >
> >
> >Martin Pala wrote:
> >
> >
> >
> >>Yet one thing - i think that it shouldn't be part of 'autostart'
> >>statement (it is intended for other task). Maybe new statement such as
> >>'automonitor [yes|no]' (it sounds strange - maybe someone will had
> >>better hint :) will be more clear, if such functionality will be added
> >>to monit.
> >>
> >>Martin
> >>
> >>Martin Pala wrote:
> >>
> >>
> >>
> >>>Yeah, not bad idea :)
> >>>
> >>>there are two ways to reach similar feature:
> >>>
> >>>1.) check process only when started under monit's control as described
> >>>Oliver - it is very simple and effective method, every cluster node needs
> >>>only one 'local' monit instance.
> >>>
> >>>2.) have monit instance failover with service as part of resource
> group - in
> >>>such case it must be installed on shared disks and when cluster
> >>>reconfiguration is initialized it will start monit process with
> resource as
> >>>well => there should be one monit instance per resource (or more
> accurately
> >>>per shared disk group on which SCSI reservation is applied). This method
> >>>doesn't require big monit modification - the only one needed will
> be to have
> >>>option for specification of monit's pid file location somewhere in the
> >>>filesystem (it should be on shared disk group). Resource failover is
> >>>transparent for monit - it needn't care about shared environment, it will
> >>>just start/stop itself and monitor/start services => cluster health and
> >>>shared storage must be monitored/maintained by other service (as
> for example
> >>>by mentioned heartbeat).
> >>>
> >>>First (Oliver's) method is similar to object registration (as in SUN
> >>>cluster's pmfadm for example) - it will allow with this extension build
> >>>simple clusters. There's yet another question - storage maintanance, two
> >>>ways i think about:
> >>>
> >>>a.) described rcscripts (monit-node1 and monit-node2, etc.) will be
> >>>responsible for storage maintenance (storage reserve/release and optionaly
> >>>forcing of it). They shouldn't start 'monit -g service start' before the
> >>>node masters the storage => it may lead to hard error before
> touching monit
> >>>subsystem (similar as in above mentioned variant 2.)
> >>>
> >>>b.) start/stop scripts involved by monit will be more
> sophisticated and will
> >>>check/maintain storage status (possible do scsi reservation in
> the case that
> >>>the node doesn't master it) before trying to start service. While monit
> >>>currently doesn't watch for return value of these scripts, in the case of
> >>>failure it will lead to service timeout on monit's level.
> >>>
> >>>
> >>>It is possible to allow one or both methods (variant 1. needs Oliver's
> >>>patch, variant 2. needs optional pid file location patch).
> >>>
> >>>+1 for Oliver's way
> >>>
> >>>Maybe it will be usefull for others to have 'howto' for building simple
> >>>clusters with use of monit :)
> >>>
> >>>Greetings,
> >>>Martin
> >>>
> >>>
> >>>----- Original Message -----
> >>>From: "Jan-Henrik Haukeland" <address@hidden>
> >>>To: <address@hidden>
> >>>Sent: Wednesday, October 23, 2002 7:47 AM
> >>>Subject: Re: additional feature for monit-3.0 (for clusters)
> >>>
> >>>
> >>>
> >>>I spoke with Oliver off list and asked him to send a mail to the list
> >>>for discussion, so does anyone have an opinion on this?
> >>>
> >>>Oliver Jehle <address@hidden> writes:
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>>when using heartbeat and groups in monit, i've missed following feature.
> >>>>
> >>>>monit should only monitor manualy started resources . and after stopping
> >>>>it, monit should stop monitor it.
> >>>>
> >>>>so i've implemented a third input value for the autostart "started". now
> >>>>monit monitors a resource only, if you start it with "monit start"...
> >>>>
> >>>>why that... see below.... it's my config for hearbeat with monit
> >>>>
> >>>>on every node
> >>>>
> >>>>/etc/inittab starts monit
> >>>>/etc/rc3.d/ script execute "monit start heartbeat"
> >>>>/etc/init.d/ monit-node1 "monit -g node1 start"
> >>>>/etc/init.d/ monit-node2 "monit -g node2 start"
> >>>>
> >>>>so hearbeat can control easy the cluster state and if one node fails,
> >>>>hearbeat starts monit-xxxx of the failing node and  monit is instructed
> >>>>to start the services of the failing-node and monitor them...
> >>>>
> >>>>
> >>>>--
> >>>>Oliver Jehle
> >>>>Monex AG
> >>>>Föhrenweg 18
> >>>>FL-9496 Balzers
> >>>>
> >>>>Tel: +423 388 1988
> >>>>Fax: +423 388 1980
> >>>>
> >>>>----
> >>>>I've not lost my mind. It's backed up on tape somewhere.
> >>>>----
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>--
> >>>Jan-Henrik Haukeland
> >>>
> >>>
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> >>>
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> >>
> >
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