2. ICT infrastructure design for axis diplomat

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This application support note is intended to provide general guidelines on the design of ICT infrastucture which will be used in conjunction with axis diplomat and/or axis payroll.

Since axis diplomat scales from a single user system which may be installed on a single Windows PC to 250 user configurations with high transaction volumes and large storage capacity requirements the design of an axis diplomat server and supporting ICT infrastucture varies considerably. 

It is possible (and practical) to run an entire axis diplomat system including its native database, MS SQL and all other requirements on a single drive partition on the same PC or server. Whilst this may be satisfactory for a single user system it will not scale!

The pupose of this document is to highlight the main design considerations. It does not purport to give detailed information on how to design ICT infrastucture for any given scenario. axis first's technical services division offers an infrastucture design consultancy service for this purpose.

Please note that unless specifically stated otherwise no third party software or hardware required to run axis diplomat is included as a part of axis diplomat. 

Server & storage architecture should take into account the following:

1. axis diplomat is a transactional database. It has similar requirements to those of any other transactional database (e.g. MS SQL) and therefore industry best practice guidance for deployment and performance considerations of transactional databases will generally apply equally to axis diplomat. Examples are:
   'Description of logging and data storage algorithms that extend data reliability in SQL Server' (see https://support.microsoft.com/en-us/kb/230785 ).
   'Information about using disk drive caches with SQL Server that every database administrator should know' (see https://support.microsoft.com/en-us/kb/234656 ).
   'Description of caching disk controllers in SQL Server' (see https://support.microsoft.com/en-us/kb/86903 )
2. axis diplomat is a native Windows application. In addition to running as a ‘fat’ client-server application it is optimised to run in a Windows RDS (Remote Desktop) environment as a thin client. Deploying axis diplomat in an RDS configuration can provide performance gains of up to 10x and therefore is highly desirable. In RDS environments the axis diplomat programs and database must be installed on the same Windows server on which the remote desktops are running in order to provide this performance advantage. When both the client and server components of axis diplomat are running within the same server, axis diplomat utilises a shared memory model for transferring data which avoids data being transferred over the TCP/IP stack (and the overhead of the Windows network redirector) resulting in the significant performance gain which can be achieved. Access to axis diplomat for remote home/mobile working is also enabled using RDS. axis diplomat can be run on a Windows RDS server which is not also hosting the axis diplomat application database however in this configuration axis diplomat clients are effectively running as 'fat' clients to the axis diplomat database sever and thus the performance advantage is lost.
3. axis diplomat is supported in both physical and MS Hyper-V virtualised Windows Server environments.
4. Both on-premise and hosted deployments are supported including cloud based solutions such as Azure. On-premise installations may utilise a mix of thin (RDS) and fat clients (Windows PCs) as appropriate. In hosted/cloud based deployments, all access is via Windows RDS.
5. Versions of Microsoft Windows supported by each release of axis diplomat are published in the supported environments list at http://www.axisfirst.co.uk/documentation/System-Requirements-for-axis-diplomat-2014/articles/11524 . In general, the business editions of versions of MS Windows which are in Microsoft mainstream support phase at the date of release of the axis diplomat version in question will be supported by axis diplomat.
6. axis diplomat requires MS SQL Server. The MS SQL Server may be run on the same server as the axis diplomat software or on a separate server. Using an installation of MS SQL on a different server has the advantage of spreading load and therefore improving performance. Complex data reporting and analysis can be run without impacting on the performance of the live transactional database. The disadvantage is that the number of components involved in the operation of the axis diplomat system is significantly increased thus making it more prone to maintenance need or failure. In this configuration, SQL data is being transmitted over the LAN infrastructure (physical or virtual) and there is another Windows Server instance to maintain on another set of server hardware. MTBF is thus reduced. An instance of MS SQL will need to have been installed and made available for use by axis diplomat prior to installing the axis diplomat software. Please note that unless specifically stated otherwise axis diplomat licensing does not include MS SQL licensing. If you require licensing for MS SQL, axis first is able to offer ISV licensing (bundled with axis diplomat licensing) at preferential rates. 
7. axis diplomat provides integration with MS Office applications including Outlook, Word and Excel. Whilst MS Office is not a mandatory requirement the functionality provided by such integration is a significant advantage to most users. Careful consideration must be given to server specification (and MS Office licensing models) in RDS environments as, in order to provide integration, the MS Office applications must run in the context of the server (not the workstation) and will therefore impact server memory, processing and storage requirements. Information on supported versions of MS Office is provided at http://www.axisfirst.co.uk/documentation/System-Requirements-for-axis-diplomat-2014/articles/11524
8. It is possible (and practical) to run an  entire axis diplomat system including its native database, MS SQL and all other requirements on a single drive partition on the same PC or server. Whilst this may be satisfactory for a single user system it will not scale. For optimal performance on larger systems:
   1. Deploy axis diplomat onto a DAS partition which is not used for anything else (this maximises the disk IO bandwidth available to axis diplomat) and which uses the fastest storage hardware your budget permits (SAS with hardware cache as a minimum).
   2. Deploy MS SQL Server on separate physical disk partitions/drives/spindles.
   3. Ensure that any RAID configuration follows best practice for transactional databases. For example: Always use a RAID configuration. Use RAID1 or 10 and never RAID5 (this is because RAID 5 is much less efficient than RAID 10 at writes). ALWAYS ensure that cache is configured for write-through operation etc.)
   4. All references to RAID throughout this document refer to hardware RAID controllers and not Windows software RAID which should not be used for performance reasons.
   5. Configure axis diplomat’s roll-forward transaction logging on a separate (fast) partition on a separate spindle to ensure that IO is dedicated to this purpose. axis diplomat roll-forward data protection uses a mechanism similar to MS SQL WAL (Write-Ahead Logging). Poor disk sub-system design can have a dramatic impact on system performance and the considerations highlighted is MS knowledgebase article 230785 (see section 1 above) should be carefully implemented.
   6. Configure axis diplomat’s backup destination to an NTFS compatible share on a NAS device. This has two advantages; firstly it reduces disk IO load on the axis diplomat server during backup or restore (thus improving backup performance and reducing recovery time) and, secondly, it provides some resilience in a Disaster Recovery scenario (especially where the NAS device is located physically distant from the server).
   7. axis diplomat utilises Windows VSS (Shadow copy) technology when taking its backups. Follow MS best practice guidelines when configuring VSS, for example, use a separate volume/spindle to eliminate the possibility of high IO load impacting performance. See https://technet.microsoft.com/en-us/library/cc753975.aspx

9. Performance can be significantly influenced by the behaviour of anti-virus software. Ensure that your chosen solution is capable of being configured along best practice guidelines for axis diplomat (see http://www.axisfirst.co.uk/documentation/Configuring-Anti-Virus-Software-with-axis-diplomat-2014/articles/11527 )

Network infrastructure will significantly determine the performance of axis diplomat.

1. 1Gb Ethernet (and not 100Mb) is required for performance reasons when running ‘fat’ client. It is also desirable (but not essential) for thin clients (improved experience on a thin client is due to reduced latency providing better responsiveness rather than any benefit being derived from increased bandwidth).
2. The use of Wi-Fi network connections for ‘fat’ clients is not practical for performance reasons (because of both bandwidth and latency). Where connectivity over Wi-Fi is required, utilise Windows RDS.
3. Consider the mechanism by which off-site (Disaster Recovery) backup will be provided. axis diplomat data may expand to many tens of GB over time. If DR backup is to be provided using remote cloud-based solutions this may require new or upgraded communications links. Alternatively DR backup may utilise removable media devices. axis diplomat includes built-in technology to create and transmit backups to axis first's servers providing off-site protection of your axis diplomat data on a subscription basis. This should not be considered as an alternative to system level backup of your server(s).

axis diplomat supports the use of Windows PCs as 'fat client' workstations where connected via a LAN at speeds of 1GB or higher. Any mix of fat client and thin client usage is supported.

Information on minimum supported specifications is provided at: http://www.axisfirst.co.uk/documentation/System-Requirements-for-axis-diplomat-2014/articles/11524

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