EVS XTAccess Version 1.16 - November 2011 User Manual - Manual (Page 42)

Issue 1.16.A XTAccess Version 1.16 – User’s Manual
Author: Serge Comes - EVS Broadcast Equipment – November 2011
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7.5 LOAD BALANCING BETWEEN MULTIPLE
XTACCESS DEVICES
Multiple XTAccess devices can scan the same XML scan folder.
In order to efficiently distribute the XML jobs over all the XTAccess devices, load
balancing rules must be defined.
7.5.1 M
ANAGEMENT OF
XML J
OBS
Once a new XML job is sent to XTAccess, several criteria are taken into account
in order to decide whether the job must be processed:
• Maximum amount of jobs simultaneously processed.
• Maximum amount of jobs simultaneously processed per IP address
• Presence of a job waiting for a connection to EVS server with the same IP
address.
Besides, the maximum amount of XML jobs that can be simultaneously processed
per XML scan module is also limited. The XML scan per folder is processed every
5 seconds.
Once a job is processed by XTAccess, the first action is an attempt to connect the
XT FTP server. In case the connection failed, 2 cases are considered:
• The connection is refused by the EVS server because the maximum amount of
connections is reached (max. 6 FTP connections for HiRes EVS servers). The
status will be “Server busy”. Unlimited connection attempts are done every 2-
4 seconds until getting an available connection.
• The connection cannot be established because the IP address is not
reachable. The status is “Server IP failed”. Several connection attempts are
done within fixed time intervals (see ‘IP Retry parameter’ in section 7.5.2
‘Control Parameters’ on page 41). After some attempts (see ‘IP Retry Timeout
parameter’ in section 7.5.2 ‘Control Parameters’ on page 41) the job will be
cancelled and an error status will be generated.
Any other failure during the connection to an EVS server will cancel the job and
generate an error “GENERAL FAILURE”.
In case a job that is processed is not able to connect, no other job with the same
IP address will be taken into account. Once the connection will be resumed by
this “blocked” job, the other waiting jobs will be processed again.
In case of XT Copy job, connection is first established to the destination EVS
server prior to the source server. In case the connection failed, the connection to
the source server is not used, in order to avoid unexpected XT FTP connections.
Every jobs are taken into account following a FIFO stack (oldest job first).