EVS XTAccess Version 1.18 - July 2012 User Manual - Manual (Page 43)

XTAccess Version 1.18 – User Manual
EVS Broadcast Equipment – July 2012
Issue 1.18.A
33
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 Management of XML Jobs
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 34).
After some attempts (see ‘IP Retry Timeout parameter’ in section 7.5.2 ‘Control
Parameters’ on page 34) 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).