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Navigator Systems NX SQL Database server Memory Settings

 

We recommend leaving the MAX RAM setting (see Server Engine) on the Navigator Systems NX SQL Database server at -1 and ensuring that your file server has sufficient memory to get the very best performance.

For full details on the Navigator Systems NX SQL Database server's memory allocation & requirements, see below.

 

A typical Database consists of many tables. Each table comprises of many records and each record comprises of several fields. Groups of records and fields are stored together in a block. If some data is requested from the server, then the whole block is read from the disk before the appropriate record or field is passed to the requester. Similarly when some data is modified, the whole block is written to disk.

For maximum speed and efficiency the Navigator Systems NX SQL Database server  will load each block, as it is requested, into memory and keep it there until it the Navigator Systems NX SQL Database server is shut down, this allows it to process subsequent data requests directly from memory, which is much faster than reading from disk.

All database edits are written to disk immediately, but via a background task within the server, so at all times there are two copies of your data: a the hard copy on disk and a working copy in memory.

 

The net effect of this model is that as more and more tables are opened and read (as users access different parts of HireTrack NX), the memory usage on the server will increase until, eventually, the whole of the database will be loaded into RAM, if it is available. If you use the Navigator Systems NX SQL Database server for multiple databases (aliases) then you will need to take all the tables in all the aliases into account when considering memory usage.

 

TIP #1.

The amount of memory available on your file server is important to the efficiency of the Navigator Systems NX SQL Database server. Since memory is cheap it is a false economy not to have plenty available.

 

TIP #2
Add 10% to your the size of all your database files (*.NX1) when calculating how much memory is required by the Navigator Systems NX SQL Database server.

 

MAX RAM Setting on the Navigator Systems NX SQL Database server

 

A. Default Value of  -1
 
the Navigator Systems NX SQL Database server will use a maximum of 50% of the physical memory available to the machine, to the limit of the maximum amount of  memory that Windows allows any application to use.
What this means practically depends on two factors: whether the application (e.g. the Navigator Systems NX SQL Database server) is a 32-bit or 64-bit application ; and whether Windows is 32-bit or 64-bit.

 

The current release of the Navigator Systems NX SQL Database server is 32-bit, although a 64-bit version is planned, hopefully for release in the latter part of 2013.

 

1.        32-bit application & 32-bit Windows
 
Normally an application limited to a maximum of 2 GB of memory, although it can be raised to 3 GB if the Windows 4GT boot flag is set. But Windows itself is limited to 4 GB of physical RAM.
 

2.        32-bit application & 64-bit Windows
 
A maximum of 4 GB of memory is available to each application and the amount of physical RAM Windows can use will depend on which version you are running. Up to 4 TB (4000 GB) is possible.
 

3.        64-bit application & 64-bit Windows
 
Applications can use up to a maximum 8 TB

 
Example # 1

 

If all of your database files (i.e those with the extension .NX1) files total 1 GB and your file server has 1.8 GB of FREE memory available (after Windows and any other applications have loaded), then with the MAX RAM set to -1, the Navigator Systems NX SQL Database server will load a maximum of  0.9 GB of your database files into memory, leaving 0.1 GB stored on disk alone, which will reduce performance slightly. In this case you should consider making more RAM available on the server machine. But even if FREE available memory was 2.0 GB you will still be in danger of running inefficiently since additional server memory often gets used for query data that is retrieved during the course of running the complex SQL statements used by client database applications.
 

 

B. Custom Value for MAX RAM
 
This value is set in Megabytes (MB) NOT Gigabytes (GB). In general you should try to have sufficient free memory available on your file server in order to leave the MAX RAM value set to the Default of -1. However, if you do have to reason to set a specific value and accept that this may reduce the performance of the Navigator Systems NX SQL Database server, bear in mind that regardless of the value you enter, the Navigator Systems NX SQL Database server will always ensure that 1 GB (1000 MB) of potential free memory available to the application is NOT used for data storage so that it can be made available for other types of memory use by the server engine. Of course if the file server has many other demands put upon it by other applications then this ambition to keep back 1GB of memory will be curtailed anyway and the Navigator Systems NX SQL Database server will be even more restricted in its efficiency.
 

Example # 2

 

If all of your database files (i.e those with the extension .NX1) files total 1 GB and your file server has 16 GB of physical memory. However, you want to restrict the amount of memory allocated to the Navigator Systems NX SQL Database server, specifically for data storage, to 500 MB so that the file server can also run other memory intensive applications such as MS SQL Server, or MS Exchange without being impaired. If you enter 500 into the MAX RAM setting, then even if significantly more memory than  500 MB is available on the file server, the Navigator Systems NX SQL Database server will never cache more than this value and each time new blocks of data need to be loaded from disk, older records in the memory will be discarded to make room for them.