[LON-CAPA-admin] Map not loaded error and missing problems/sequence file

[Stuart Raeburn]

Eric,

It turns out that this error occurred because of the protracted copy  
history of this folder (resulting in an ever lengthening filename).   
LON-CAPA hostID changes associated with access server  
additions/switches were likely not a factor.

Eventually the filename when copying this .sequence file ran up  
against a 255 character limit for names, imposed by the OS. Although  
the actual name itself is still less than 255 character limit, a  
temporary file used in the replication process from  
/home/httpd/html/userfiles to permanent storage in  
/home/httpd/lonUsers/vcu/7/x/2/7x23751c9d5a248edvcua1 receives the  
suffix: '.in.transit' which exceeds the 255 limit.

The forthcoming release of LON-CAPA 2.8 provides a solution for this  
issue (by eliminating the use of such long filenames) and also checks  
that copying was successful before updating the map into which the  
course coordinator was attempting to paste the copied file.

In the meantime, a solution which is consistent with the LON-CAPA  
philosophy would be for the Course Coordinator to create a version of  
this sequence file (which is apparently copied over and over) in  
Construction Space, and then publish it.  The contents of the sequence  
could then be imported into a newly created folder in the Course  
Editor whenever this particular set of resources was to be used.   
After import into a course, resources in the new folder can be deleted  
(if not required), or re-ordered etc.

You should see an error message in /home/httpd/perl/logs/lond.log on  
the vcu library server.

LWP GET: 500 Cannot write to  
'/home/httpd/lonUsers/vcu/7/x/2/7x23751c9d5a248edvcua1/userfiles/default_121888532420408122049661886012210909623064612216167072554812223520052745012223628802987112228847403262012235880253271812241782867629122463704767051225464849592122605977910350122659821911240122710968986191227882594282761228426065.sequence.in.transit ':  File name too  
long

(Acknowledgements to Guy Albertelli (LON-CAPA Technical Director,  
Emeritus) for passing on the hint about OS-based restrictions on  
filename length).

Stuart Raeburn
MSU LON-CAPA group

Quoting Stuart Raeburn <raeburn at msu.edu>:

> Eric,
>
> One question here is: which server was the CC logged into when the
> particular folder was copied in DOCS?
>
> For this particular case (where copying an existing folder failed)
> these warnings can be eliminated by clicking the "continue" link from
> the course initialization page which displays these "Map not loaded"
> messages and then via 'Edit Course' deleting the folders corresponding
> to these non-existent sequence files.
>
> It should be apparent which are the folders for which copying failed
> because in the Navigate Contents page I would expect they would be
> designated by jigsaw piece icons, instead of folder icons.  Obviously,
> for each the url in the link for the jigswa piece should be checked
> against the names of the files generating the "Map not loaded" messages
> to check that the correct item has been identified before deletion.
> Name checking unfortunately will be somewhat painful given such a long
> file name (indicative of an extensive clone/copy history for the
> particular folder).
>
> What happened here was that LON-CAPA updated the contents of the
> top-level sequence (default.sequence) with references to these "copied"
> folders, but the actual copying of the files had failed somewhere.
>
> You'll find records in /home/httpd/perl/logs/lonnet.log on the server
> which was hosting the CC's session when copying failed, and possibly
> also in /home/httpd/perl/logs/lond.log on the library server if a
> problem occurred when trying to replicate the new sequence file from
> the server hosting the session to  permanent storage on the course's
> library server.
>
> If the CC was logged into the library server when the copy folder
> action was carried out on the library server, your addition of a new
> access server and subsequent switching of IP addresses on the access
> servers would be unrelated to this copy failure.  However, if the
> session was hosted on one of the access servers it is possible I
> suppose that the library server could not connect to the access server
> where the copy occurred. This behavior would depend on the timing of
> propagation of DNS changes in your network, and the timing of
> refreshing of cached ip/host information used by the Apache children.
>
> From a LON-CAPA perspective it's clear that the return value of
> &Apache::lonclonecourse::writefile() needs to be checked in londocs.pm
> before updating the map into which the user was attempting to paste the
> copied file. This will be fixed for the next release.
>
> Stuart Raeburn
> MSU LON-CAPA group
>
> Quoting Eric Harvey/FS/VCU <teharvey at vcu.edu>:
>
>> Hi,
>>
>> Just added a new server to lon-capa at VCU and I'm wondering if that
>> hasn't created a problem.
>> I get this error while attempting to access a course on the new server or
>> the library server.
>> The actual file doesn't exist when I look for it at the command line on
>> the library server.
>>
>> The following problems occurred:
>> Map not loaded: The file
>> /home/httpd/html/userfiles/vcu/7x23751c9d5a248edvcua1/default_121888532420408122049661886012210909623064612216167072554812223520052745012223628802987112228847403262012235880253271812241782867629122463704767051225464849592122605977910350122659821911240122710968986191227882594282761228426065.sequence
>> does not exist.
>>
>> The instructor of the course writes:
>> "When using the copy and paste command on the indicated directory, the
>> problems inside the directory seemed to no longer exist.
>> When I repeated the process this morning, the HW#14 directory successfully
>> copied once and did not copy another time.
>> So, it is not simply a corrupted directory.  I used all three servers and
>> there was no particular pattern."
>>
>> Thanks,
>> Eric Harvey
>> VCU Learning Systems
>>
>
>
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