# `disk`

Disk usage of the mounted filesystems (`statvfs`), read every 10 s
while a reader is visible. While none is but a `graph` keeps history
of it, it reads at the coarser of that and a twentieth of the
graph's `history`; otherwise not at all.

| Field | Type | |
| --- | --- | --- |
| `usage` | `float` | The root filesystem's fraction in use, 0 to 1: `pct(disk.usage)`. |
| `used` | `float` | The root filesystem's bytes in use. |
| `total` | `float` | The root filesystem's size in bytes. |
| `free` | `float` | The root filesystem's bytes free to a user. |
| `all` | `[Filesystem]` | Every mounted filesystem on a local disk, `/` first, keyed by `path`. |