[Go-essp-tech] verification of datanode status

[Henrik Wiberg]

The datasets are published from a virtual machine running on a server at
DMI. The problem is that the virtual machine has totally crashed and is
not possible to start.

If the virtual machine had 'real' data this would be disastrous (even
though the data was stored another filesystem and the virtual machine
used a 'shared drive'. In this case it was only testdata.

Since it will not be possible to unpublish the data from the datanode,
the datasets metadata has to be removed from the gateway.

/Henrik

mån 2011-12-19 klockan 16:15 -0800 skrev Karl Taylor:
> Hi All,
> 
> No matter what, it seems that published datasets that are not
> available should be "unpublished" (unless this is a temporary
> situation).  In the case under discussion, could someone tell me whom
> to contact at DMI to ask them to do this (or better yet, write them
> yourself, if that will work).  
> 
> I'm curious ...  what model output looks like it is currently
> available from DMI but really isn't?
> 
> thanks,
> Karl
> 
> On 12/19/11 2:02 PM, Eric Nienhouse wrote: 
> > Hi All,
> > 
> > A long standing Gateway requirement is to provide search and discovery 
> > of datasets (and other metadata) regardless of the state of remote 
> > services.  In the event that a data node service is unavailable, users 
> > should still be able to identify datasets, determine what has been 
> > published and generate download scripts.
> > 
> > This guiding requirement was discussed at great length by the ESG-CET 
> > project group and was accepted as a key element in support of the 
> > community's best interest for data discovery.  Identifying "what has 
> > been published" was a key use case driving this need.  This advantage of 
> > this approach is that it allows users to find out "what exists" during 
> > periods of unexpected downtime or other service unavailability.
> > 
> > Henrik noted that the DMI data node is no longer serving datasets 
> > publishing into ESG.  In this case these datasets can be discovered at 
> > the Gateway, however, they are inaccessible and out of sync.  If these 
> > data are no longer meant to be accessed, I'd suggest they be "retracted" 
> > from the gateway and they will no longer appear in the search results.
> > 
> > Thanks,
> > 
> > -Eric
> > 
> > Estanislao Gonzalez wrote:
> > > T(sorry the message got cut)
> > > ...it's up to the publisher to define when data shouldn't be accessible 
> > > anymore.
> > > 
> > > There are some improvements that can be doen, but most I can think of 
> > > will make the understanding of the system more complex to the end user.
> > > 
> > > Datanode admin should rely on tools that help them get their nodes up 
> > > for as long as possible (nagios & Co).
> > > 
> > > My 2c,
> > > Estani
> > > On 19.12.2011 08:04, Estanislao Gonzalez wrote:
> > >   
> > > > Hi Luca,
> > > > 
> > > > That's not what Henrik meant. Neither the architecture retains a 
> > > > living
> > > > link to a data nose (not an index one, as you've pointed out)
> > > > 
> > > > This is a feature IMO as the search engine is detached from the
> > > > dataone. The index might indeed "prune" the data nodes down, but 
> > > > unless
> > > > this is done synchroneusly it would difficult the federation
> > > > interaction.
> > > > Or to say it differently: Is up to the data node to assure data is
> > > > available, and if that's not desired anymore, On 19.12.2011 07:15,
> > > > Cinquini, Luca (3880) wrote:
> > > >     
> > > > > Hi Henirik,
> > > > > 	not sure about the gateway, but this is a feature the P2P system
> > > > > does have: has soon as a datanode is inaccessible, the search
> > > > > automatically prunes that node away, so the search results never
> > > > > contain dead links.
> > > > > thanks, Luca
> > > > > 
> > > > > On Dec 19, 2011, at 3:58 AM, Henrik Wiberg wrote:
> > > > > 
> > > > >       
> > > > > > Does the gateway somehow 'ping' its registered datanodes to verify
> > > > > > that
> > > > > > they are accessible? The datanode at dmi has not been running for 5
> > > > > > mounts still the datanodes published datasets are searchable and
> > > > > > displayed at the gateway cmip-gw-badc. Should not inaccessible
> > > > > > datasets
> > > > > > be removed from the search result?
> > > > > > 
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