How to Enable SSD Cache in CubeCOS Storage Pools

In CubeCOS storage architecture, enabling storage cache is primarily aimed at improving storage access performance, reducing latency, and minimizing I/O pressure on the backend storage systems. This feature is commonly used with backend storage solutions such as Cinder (block storage) or Ceph.

Accessing CubeCOS cluster VIP via SSH

Log into CubeCOS with your admin credentials to begin flash cache configuration.

ssh admin@<your-cluster-vip>

Warning: Permanently added '192.168.1.x' (ECDSA) to the list of known hosts.
Password:

Check the storage cache status

Check the storage cache status before beginning with configuration.

controller> storage
controller:storage> cache
controller:cache> status
STATUS: off

Enable the SSD cache

Enable the SSD cache with cache switch command, and enter on to turn on the SSD cache.

controller:cache> switch
Current cache status: off
Turn on/off the cache(on/off): on

Verify SSD cache enablement

Verify that the SSD cache has been enabled with status command.

controller:cache> status
STATUS: on
USED	SIZE
--
0.34	223GiB
--

[Optional] Promote/ demote disk tiers

Disks might occasionally be misidentified (e.g., SSD detected as HDD, HDD detected as SSD). Use the promotion or demotion mechanism to enforce the correct storage medium type.

Promote a disk

controller:storage> promote_disk
  index          name      size   storage ids
--
      1      /dev/sdb    238.5G           0 1
      2      /dev/sdc    931.5G           2 3
--
Enter the index to promote: 1

Demote a disk

controller:storage> demote_disk
  index          name      size     osd              serial
--
      1      /dev/sda    745.2G     0 1  BTWA632602ZU800HGN
      2      /dev/sdb    745.2G     2 3  BTWA632601U9800HGN
      3      /dev/sdc    745.2G     4 5  BTWA632602Q0800HGN
      4      /dev/sdd    745.2G     6 7  BTWA632605GP800HGN
      5      /dev/sde    745.2G     8 9  BTWA63260373800HGN
      6      /dev/sdf    745.2G   10 11  BTWA632601ZJ800HGN
      7      /dev/sdg    745.2G   12 13  BTWA6326047A800HGN
      8      /dev/sdh    745.2G   14 15  BTWA632604RJ800HGN
      9      /dev/sdi    745.2G   16 17  BTWA632602Q3800HGN
     10      /dev/sdj    745.2G   18 19  BTWA632605EV800HGN
     11      /dev/sdk    745.2G   20 21  BTWA632601X9800HGN
     12      /dev/sdm    745.2G   22 23  BTWA6326038Z800HGN
     13      /dev/sdn    745.2G   24 25  BTWA632601RW800HGN
     14      /dev/sdo    745.2G   26 27  BTWA63250476800HGN
--
Enter the index to demote: 1