# Disk I/O

Glances displays the disk I/O throughput, count and mean latency: - bytes per second (default behavior / Bytes/s, KBytes/s, MBytes/s, etc) - requests per second (using –diskio-iops option or B hotkey) - mean latency (using –diskio-latency option or L hotkey)

It’s also possible to define:

- a list of disk to show (white list)

- a list of disks to hide

- aliases for disk name (use to espace special characters)

under the `[diskio]` section in the configuration file.

For example, if you want to hide the loopback disks (loop0, loop1, …) and the specific `sda5` partition:

    [diskio]
    hide=sda5,loop.*

or another example:

    [diskio]
    show=sda.*

Filtering is based on regular expression. Please be sure that your regular expression works as expected. You can use an online tool like regex101 in order to test your regular expression.

Note

When a disk has an `alias` defined, the `hide` and `show` patterns are evaluated against both the original device name and its alias, and the disk is hidden (or shown) if either matches. This means a “negative-lookahead” allow-list pattern such as `hide=^(?!(?:nvme[0-9]+n[0-9]+$|sd[a-z]+$)).*` will inadvertently match aliases that do not follow the device naming scheme (e.g. `my_data_disk`) and therefore hide every aliased disk. Prefer `show=` for allow-list semantics, or write explicit `hide=` patterns that target the names you actually want to exclude.

It is also possible to define thesholds for latency and bytes read and write per second:

    [diskio]
    # Alias for sda1 and sdb1
    #alias=sda1:SystemDisk,sdb1:DataDisk
    # Default latency thresholds (in ms) (rx = read / tx = write)
    rx_latency_careful=10
    rx_latency_warning=20
    rx_latency_critical=50
    tx_latency_careful=10
    tx_latency_warning=20
    tx_latency_critical=50
    # Set thresholds (in bytes per second) for a given disk name (rx = read / tx = write)
    dm-0_rx_careful=4000000000
    dm-0_rx_warning=5000000000
    dm-0_rx_critical=6000000000
    dm-0_rx_log=True
    dm-0_tx_careful=700000000
    dm-0_tx_warning=900000000
    dm-0_tx_critical=1000000000
    dm-0_tx_log=True

You also can automatically hide disk with no read or write using the `hide_zero` configuration key. The optional `hide_threshold_bytes` option can also be used to set a threshold higher than zero.

    [diskio]
    hide_zero=True
    hide_threshold_bytes=0