Administrator’s Guide

22 FileMaker Server Administrator’s Guide
Mac OS: To change database properties, choose View menu >
Configure
, then click the Databases tab.
Setting the maximum number of files
You can specify the maximum number of database files
FileMaker
Server can host at one time. If you consistently monitor
database usage, you can set the maximum number of files for best
performance on your server. For information on performance and
optimizing memory settings, see Help.
Changing the amount of memory used by
FileMaker Server
Use Reserve n MB of RAM for database cache to specify a cache size
for FileMaker
Server. Increasing the RAM reserved for the database
cache can speed up overall performance for a correctly designed
database, especially if your server hosts large files or a large number
of clients or files.
For information on performance and optimizing memory properties,
see Help.
Setting the cache flushing distribution interval
FileMaker Server 7 uses an improved cache flushing algorithm. In
FileMaker Server
7, the cache is constantly being flushed. The cache
flushing routine scans the cache, looking for pages that have
changed. FileMaker Server
7 inspects up to 1/60th of the cache and
writes any changed pages it discovers to the disk. The process repeats
continuously, writing 1/60 of the cache to disk every second, even
during scheduled backups.
For example, in a 64MB cache, FileMaker Server will inspect up to
1/60th of the cache, or a little more than a megabyte, and flush all of
the changed records it finds. It will then wait a second and begin
again, inspecting up to 1/60th of the cache, looking for changed
records. This method of flushing the cache distributes writing to the
hard disk over the span of a minute.
By default, the cache flush mechanism will attempt to scan the entire
cache in a minute. In most cases this means all cached changes on the
server will be no more than one minute old, although database size
and hard disk speed can affect these results.
To change this behavior and spread the cache flushing over a longer
period of time, select
Distribute cache flush over (hh:mm). Unsaved
changes in FileMaker Server will be no older than the interval you
specify. FileMaker Server reduces the amount of data to inspect
every second to a smaller value, down to 128k per second.
This property determines how much cache is flushed each second.
Before deciding to change this property the administrator must
balance cache size against the risk of data loss in the event of a
computer failure. Locations that require maximum performance and
are less concerned about the potential for lost data can use a longer
cache flush distribution interval, while locations that want maximum
data integrity should use a smaller cache flush distribution interval.
For example, if the value is set to 10 minutes with a 64MB cache, the
engine will inspect 1/600th of the cache each second, or about 110K
of cache, (less than the minimum, so the engine will actually inspect
128K of cache) and write only the changed data to disk. However, if
this interval is set to 10 minutes with a 500 MB cache, it will only
inspect 853K as opposed to the default value of 1/60th of the cache,
or 8.5 MB. Used this way, the server can distribute its disk writing
over time, and therefore allow the server CPU a higher priority to
service client requests, as it will take much less time to inspect 853k
compared to 8.5MB.