The Cache Manager may occasionally be unable to write cached data back to a File Server machine, possibly because the File Server machine is down or because network problems prevent the Cache Manager from reaching it. In this event, the Cache Manager displays a message on the screen to notify the user that it cannot write the data to the File Server machine. If possible, it also returns a failure code to the application program that is using the data.
The Cache Manager keeps the unstored data in the cache and continues to attempt to contact the File Server machine until it can store the data. (The frequency with which the Cache Manager attempts to reach a File Server machine is defined with the -pollinterval option of the fxd command issued on that File Server machine.) In the meantime, corrective measures can be taken to alleviate the problem that prevents the data from being stored; for example, the File Server machine can be restarted. Once the problem is alleviated, the Cache Manager can contact the File Server machine and store the data.
The Cache Manager discards unstored data only when
· It needs to make room in the cache for other data. Given an average-sized cache with average usage, the Cache Manager rarely needs to discard unstored data.
· The cm resetstores command is issued to force the Cache Manager to discard unstored data from the cache. This command cancels the Cache Manager's continued attempts to contact unavailable File Server machines; all data that the Cache Manager cannot store to such File Server machines is discarded; you cannot selectively discard individual files or data from specific filesets.
The cm resetstores command affects only data that could not be written to a File Server machine; it does not affect other data in the cache. Nonetheless, issue the command only after issuing the cm lsstores command. The cm lsstores command lists the fileset ID numbers of filesets that contain data that the Cache Manager cannot write to a File Server machine. Examine the output of the command to be sure that you know from which filesets unstored data will be discarded. You may be able to use this information to ensure that unstored data from the indicated filesets can safely be discarded.
Note: Because unstored data discarded from the cache cannot be recovered, any problem that prevents data from being written to a File Server machine should be handled promptly.
You can use the cm statservers command to determine which File Server machines are failing to respond to the Cache Manager. (See Checking File Server Machine Status for information about the cm statservers command.)
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