# Memory

Glances uses two columns: one for the `RAM` and one for the `SWAP`.

If enough space is available, Glances displays extended information for the `RAM`:

Stats description:

- percent: the percentage usage calculated as (total-available)/total*100.

- total: total physical memory available.

- used: memory used, calculated differently depending on the platform and designed for informational purposes only. It’s compute as following: used memory = total - free (with free = available + buffers + cached)

- free: memory not being used at all (zeroed) that is readily available; note that this doesn’t reflect the actual memory available (use ‘available’ instead).

- active: (UNIX): memory currently in use or very recently used, and so it is in RAM.

- inactive: (UNIX): memory that is marked as not used.

- buffers: (Linux, BSD): cache for things like file system metadata.

- cached: (Linux, BSD): cache for various things (including ZFS cache).

Additional stats available in through the API:

- available: the actual amount of available memory that can be given instantly to processes that request more memory in bytes; this is calculated by summing different memory values depending on the platform (e.g. free + buffers + cached on Linux) and it is supposed to be used to monitor actual memory usage in a cross platform fashion.

- wired: (BSD, macOS): memory that is marked to always stay in RAM. It is never moved to disk.

- shared: (BSD): memory that may be simultaneously accessed by multiple processes.

- percent_min: the minimum memory usage percentage observed since Glances startup.

- percent_max: the maximum memory usage percentage observed since Glances startup.

- percent_mean: the mean memory usage percentage observed since Glances startup.

It is possible to display the available memory instead of the used memory by setting the `available` option to `True` in the configuration file under the `[mem]` section.

A character is also displayed just after the MEM header and shows the trend value:

Trend | Status
--- | ---
`-` | Mean 15 lasts values equal mean 15 previous values
`↓` | Mean 15 lasts values is lower mean 15 previous values
`↑` | Mean 15 lasts values is higher mean 15 previous values

Alerts are only set for used memory and used swap.

Legend:

RAM/Swap | Status
--- | ---
`<50%` | `OK`
`>50%` | `CAREFUL`
`>70%` | `WARNING`
`>90%` | `CRITICAL`

Note

Limit values can be overwritten in the configuration file under the `[memory]` and/or `[memswap]` sections.