7.7.1.12 ALTER PMEMCACHE
Purpose
The ALTER PMEMCACHE
command can alter the set of cell disks used by PMEM cache, flush dirty blocks from PMEM cache, or cancel a previous flush operation on the specified cell disks to re-enable caching.
Note:
The ALTER PMEMCACHE
command can only be used
on Exadata X8M and X9M storage server models.
Syntax
ALTER PMEMCACHE { ALL | CELLDISK="cdisk1 [,cdisk2] ..." [FORCE]}}
{FLUSH [NOWAIT] | CANCEL FLUSH}
Usage Notes
-
The
ALL
option affects all available PMEM cell disks. -
The
CELLDISK
option allows you to specify individual cell disks. cdiskn represents a cell disk name. -
The
FLUSH
option synchronizes dirty data from the PMEM cache to the cell disks. Dirty data is data that has been modified in the cache but not yet synchronized with the data on disk. Synchronization of dirty data can be a lengthy process, depending on the number of bytes to be synchronized. Use the following command to check the progress of the flush operation:LIST CELLDISK ATTRIBUTES name, flushstatus, flusherror
Note:
TheFLUSH
option stops new data from being cached on the PMEM cache until CELLSRV restarts, or the flush operation is canceled with theALTER PMEMCACHE CANCEL FLUSH
command. -
The
CANCEL FLUSH
option terminates an earlier flush operation, and reinstates PMEM caching. -
The
NOWAIT
option allows theALTER
command to complete while the flush operation is in progress. - The
FORCE
option can be used to forcefully change the set of cell disks used by the PMEM cache. -
On Exadata X8M and X9M systems with Oracle Exadata System Software release 23.1.0, you can interchangeably use
ALTER XRMEMCACHE
instead ofALTER PMEMCACHE
.
Example 7-65 Using the ALTER PMEMCACHE Command
The following command specifies that the PMEM cache uses all PMEM cell disks.
CellCLI> ALTER PMEMCACHE ALL
The following command specifies that the PMEM cache uses only two PMEM cell disks, ignoring any errors or warnings.
CellCLI> ALTER PMEMCACHE CELLDISK='PM_01_mycell, PM_03_mycell' FORCE
The following command specifies initiates a flush operation for all PMEM cell disks, and returns the prompt before the operation completes.
CellCLI> ALTER PMEMCACHE ALL FLUSH NOWAIT
Parent topic: ALTER