The solution is to adjust a few parameters on the Cache Parameters tab in the SNFX control panel
(cvntclnt). These parameters control how much memory is consumed by the directory cache, the buffer cache, and the local file cache.
As always, an understanding of the customer's workload aid in determining the correct values. Tuning is not an exact science, and requires some
The settings in the Cache Parameters tab are relevant to the selected CAUTION file system only. When running multiple file systems it is necessary to adjust the Cache Parameters settings for EACH file system. Also, the
total amount of memory consumed is the SUM of the Cache Parameters settings for ALL file systems.
Settings and Parameters
•Directory Cache Size - The first setting to consider is the Directory Cache Size. The default is 10 (MB). If you do not have large directories, or do not perform lots of directory scans, this number can be reduced to 1 or 2MB. The impact will be slightly slower directory lookups in directories that are frequently accessed. Also, in the Mount Options tab, you should set the Paged DirCache option to allocate the specified memory from paged pool instead of the default
•Buffer Cache NonPaged Pool Usage - The next parameter is the Buffer Cache NonPaged Pool Usage; the value is in percent (%) and represents the percentage of available
•Watermarks - The following parameters control how many file structures are cached on the client; they are. These are controlled by the
Each cvnode is approximately 1462 bytes in size and is allocated from the
These values should be adjusted so that the cache does not bloat and consume more memory than it should. These values are highly dependent on the customer's workload and access patterns. Values of 512 for the High water mark will cause the cvnode cache to be purged when more than 512 entries are present. The cache will be purged until the low water mark is reached, for example
128.The Max water mark is for situations where memory is very tight. The normal purge algorithms takes access time into account when determining a candidate to evict from the cache; in tight memory situations (when there are more than the maximum entries in the cache), these constraints are relaxed so that memory can be released. A value of 1024 in a tight memory situation should work.
6 | April 2006, ADIC |