# Shared Storage System (BASTO)

```{admonition} Critical Warning
:class: danger
**AUTOMATIC FILE DELETION IS ENABLED** on this storage system. Read this section
  carefully before storing any data.
```

## Overview
Several "burros" (currently **dalia**, **deimos**, **diva**,
**divan**, **doctor**, **domino** and **dunedain**) have access to a ~700 TB shared storage
system hosted in a BSC-provided disk rack, accessible via the `/storage/scratch`
mountpoint.

To prevent the storage from becoming full and to maintain equitable access for
all IAC users, we have implemented an automatic file deletion policy.

## Storage Health Levels

The system operates under three capacity thresholds:

+ **Green**: below 85% capacity (normal operation)
+ **Yellow**: between 85% and 90% capacity (cleanup recommended)
+ **Red**: above 90% capacity (automatic deletion triggered)

**Yellow zone**: Users will be notified and encouraged to delete unnecessary
  files to return to green status.

**Red zone**: AUTOMATIC DELETION activates and removes files until usage drops
  to 84%.

```{note}
From the command line you can check the usage of the system with the `df` command:
``` 

```
user@burro$ df -h /storage/
Filesystem                          Size  Used Avail Use% Mounted on
10.1.1.7@tcp:10.1.1.8@tcp:/storage  693T  204T  454T  31% /storage

```

## Automatic Deletion Policy

When automatic deletion is triggered, files are selected for removal in the
following priority order:

1. **Files not accessed in 1+ year**:
   - First, files from the top five users by total storage consumption (in descending order)
   - Then, remaining files in order of oldest access time

2. **If still above 84%: Files not accessed in 6+ months**:
   - Same prioritization: top five users first, then by access time

3. **If still above 84%: Files not accessed in 3+ months**:
   - Same prioritization as above

4. **If still above 84%: Files accessed within the last 3 months**:
   - Same prioritization (unlikely to be needed)

**Rationale**: This policy removes unused files while prioritizing those from
  the heaviest users, ensuring fair storage distribution across all IAC users.

## Notifications

Status changes in the storage health levels trigger automatic notifications in
the **#computing/storage** Zulip channel.

**⚠️ If you store data in BASTO, you are STRONGLY ENCOURAGED to subscribe to this
  channel to receive deletion warnings.**