8464ch09_Oper.fm Draft Document for Review February 7, 2020 3:15 pm In ascending order of occurrence, the following thresholds are available: GLYPH<SM590000> Automatic Removal GLYPH<SM590000> Limited free cache space warning GLYPH<SM590000> Out of cache resources – HYDME0997W – HYDME1133W – HYDME1201W – HYDME0996W – HYDME1200W The policy removes the oldest logical volumes from the disk-only TS7700 cache if a  consistent copy exists elsewhere in the grid. This state occurs when the cache is 4 TB  below the out-of-cache-resources threshold. In the automatic removal state, the TS7700  automatically removes volumes from the disk-only cache to prevent the cache from  reaching its maximum capacity. This state is identical to the  limited-free-cache-space-warning state unless the Temporary Removal Threshold is  enabled. Automatic removal can be disabled within any specific TS7700 cluster by using the  following library request command: LIBRARY REQUEST,CACHE,REMOVE,{ENABLE|DISABLE} Automatic removal is temporarily disabled while disaster recovery write protect is enabled  on a disk-only cluster so that a disaster recovery test can access all production  host-written volumes. When the write protect state is lifted, automatic removal returns to  normal operation. This state occurs when less than 3 TB of free space remains in the cache. After the cache  passes this threshold and enters the limited-free-cache-space-warning state, write  operations can use only an extra 2 TB before the out-of-cache-resources state is  encountered.  When a TS7700 cluster enters the limited-free-cache-space-warning state, it remains in  this state until the amount of free space in the cache exceeds 3.5 TB. The following  messages can be displayed on the MI during the limited-free-cache-space-warning state: For more information, see IBM Knowledge Center. Clarification:  Host writes to the disk-only TS7700 cluster and inbound copies continue  during this state. This state occurs when less than 1 TB of free space remains in the cache. After the cache  passes this threshold and enters the out-of-cache-resources state, it remains in this state  until the amount of free space in the cache exceeds 3.5 TB.  When a TS7700D cluster is in the out-of-cache-resources state, volumes on that cluster  become read-only and one or more out-of-cache-resources messages are displayed on  the MI. The following messages can display: For more information, see IBM Knowledge Center. 570  IBM TS7700 Release 5.0 Guide