11.14 Managing available space in the data storage

When true is specified in the eads.cache.limiter.enable parameter, the amount of data that can be stored in EADS servers (number of stored keys, available space in the explicit heap, available space in cache files) is monitored. If a shortage of storage space is foreseen, you can set an error in the corresponding processing to prevent the EADS servers from being shut down. This is called the total data restriction function.

When the total data restriction function is enabled, the number of keys, the capacity of the explicit heap, and the capacity of cache files are monitored so that the following maximum limits are not exceeded:

• Maximum number of keys

  eads.cache.keyCount parameter value in the shared properties

• Maximum capacity of the explicit heap (megabytes)

  Maximum capacity of the explicit heap (megabytes) = (eads.java.external.heapsize parameter value in the shared properties 0.97 - eads.replication.external.heapsize parameter value in the shared properties) eads.replication.factor parameter value in the shared properties

  Notes:

  A value of less than 1 megabyte is truncated.

• Maximum capacity of cache files (megabytes)

  Maximum capacity of cache files (megabytes) = (eads.cache.disk.filenum parameter value in the cache properties - 2) (eads.cache.disk.filesize parameter value in the cache properties 1,024 - eads.cache.disk.blocksize parameter value in the cache properties 2) 1,024

  Notes:

  A value of less than 1 megabyte is truncated.

Tip

When the total data restriction function is enabled and any of these maxima is expected to be exceeded as a result of storing data (a shortage of space might occur in the storage), the processing results in an error. Therefore, if an attempt is made to perform multiple processes that store data concurrently when available storage space is limited, the processes might result in an error.

When you use the total data restriction function, your estimates of the number of keys, the capacity of the explicit heap, and the capacity of cache files need to be set to values that are larger than the actual values.

For details about the estimation method when using the total data restriction function, see 4. Checking the Required Resources.

Note that the total data restriction function is disabled temporarily while any of the following types of processing is being performed:

• Scale-out processing

• Importing data (eztool import command)

• Relocating persistent data (eztool importecf command)

• Resuming caches (eztool resume command)

Organization of this section

• 11.14.1 How to manage available space in the data storage (using only memory caches)

• 11.14.2 How to manage available space in the data storage (using disk caches)

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