# How to Enable SSD Cache in CubeCOS Storage Pools

> Learn how to enable cluster-level storage caching to improve access performance in hybrid storage deployments.

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 {#accessing-cubecos-cluster-vip-via-ssh}

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

```bash
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}

Check the storage cache status before beginning with configuration.

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

## Enable the SSD cache {#enable-the-ssd-cache}

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

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

## Verify SSD cache enablement {#verify-ssd-cache-enablement}

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

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

## [Optional] Promote/ demote disk tiers {#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 {#promote-a-disk}

```bash
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 {#demote-a-disk}

```bash
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
```