Quantum 6-01376-05 User Manual

  StorNext File System Tuning

Windows Memory Requirements

StorNext File System Tuning Guide

23

mysteriously dying, repeated FSM reconnect attempts, and messages 

being sent to the application log and

about socket failures with 

the status code (10555) which is ENOBUFS.
The solution is to adjust a few parameters on the 

 

 tab in 

the SNFS control panel (

). 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 customers’ workload aids in 

determining the correct values. Tuning is not an exact science, and 

requires some trial-and-error (and the unfortunate reboots) to come up 

with values that work best in the customer’s environment.
The first is the 

. 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 2 MB. The impact will be slightly slower 

directory lookups in directories that are frequently accessed.
Also, in the 

 

 panel, you should set the 

 

 

option.
The next parameter is the 

 

. This value 

is in percent (%) and represents the percentage of available non-paged 

pool that the buffer cache will consume. By default, this value is 75%. 

This should be set to 25 or at most 50. The minimum value is 10 and the 

maximum value is 90.
The next parameters control how many file structures are cached on the 

client. These are controlled by the 

 

, 

 

 and 

. Each file 

structure is represented internally by a data structure called the 

“cvnode.” The cvnode represents all the state about a file or directory. 

The more cvnodes that there are encached on the client, the fewer trips 

the client has to make over the wire to contact the FSM.
Each cvnode is approximately 1462 bytes in size and is allocated from the 

non-paged pool. The 

 cache is periodically purged so that unused 

entries are freed. The decision to purge the cache is made based on the 

, 

, and 

 water mark values. The 'Low' default is 1024, the 

'High' default is 3072, and the 'Max' default is 4096.
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 customers work load and access patterns. Values of 512 

for the 

 water mark will cause the 

 cache to be purged when 

more than 512 entries are present. The cache will be purged until the low