ASA Database Administration Guide
The Database Server
The database server
Database server options
Set the initial memory reserved for caching database pages and other server information.
{ dbsrv9 | dbeng9 } -c {
integer |
integerG |
integerK |
integerM |
integerP } ...
All operating systems and servers.
The amount of memory available for use as a database server cache is one of the key factors controlling performance. You can set the initial amount of cache memory using the -c server option
The more cache memory that can be given the server, the better its performance.
The units G, K, and M can be either lower case or upper case. If G, K, or M is not supplied, any integer less than 10 000 is assumed to be in kilobytes, and any integer 10 000 or greater is assumed to be in bytes. For example, -c 4096 means 4096 kb or 4 194 304 bytes, whereas -c 200 000 means (an unreasonably small) cache of 200 000 bytes.
The unit P is a percentage of the physical system memory, and if you use this, the argument is a percentage. You can use % as an alternative to P, but as most non-UNIX operating systems use % as an environment variable escape character, you must escape the % character. To use 50 percent of the physical system memory, you would use the following:
dbeng9 -c 50%% ...
If no -c option is provided, the database server computes the initial cache allocation as follows:
It uses the following operating-system-specific default cache sizes:
Windows CE 600K
Windows NT/2000/XP, Windows 95/98/Me, NetWare 2 Mb
UNIX 8 Mb
It computes a runtime-specific minimum default cache size, which is the lesser of the following items:
25% of the machine's physical memory
The sum of the sizes of the main database files specified on the command line. Additional dbspaces apart from the main database files are not included in the calculation. If no files are specified, this value is zero.
It allocates the greater of the two values computed.
NetWare database serverThere is a tradeoff between memory for the database server and memory for the NetWare file system buffers. A larger database server cache will improve database server performance at the expense of NetWare file system performance. If the database server cache is too big, NetWare will report an error that there is insufficient memory for cache buffers.NetWare memory requirements increase with every new directory and file on the file server. To track memory usage on the NetWare server, load monitor.nlm (if it is not already loaded) and select "Resource Utilization". Extra memory for your NetWare server computer could improve database performance and/or file server performance dramatically. |
The following example, entered all on one line, starts a server named myserver that starts with a cache size of 3 Mb and loads the sample database:
dbeng9 -c 3M -n myserver "C:\Program Files\Sybase\SQL Anywhere 9\asademo.db"