Cache

The cache is essential for the IO performance. It “masks” considerably slower access times of the physical disks and must therefore be adequately dimensioned:

• In OLTP mode it should be possible to achieve a read hit rate of at least 80%, preferably higher.

• The write hit rate should always be around 100%. Write hit rates below 100% either indicate that the cache is too small or are the result of an acute overload of specific RAID groups which are not powerful enough.