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Add data retention policy #188

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57 changes: 57 additions & 0 deletions doc/design/data-retention-policy.md
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# Data Retention Policy

Dandihub data storage on AWS EFS is expensive, and we suppose that significant portions of the data
currently stored are no longer used. Data migration is where the cost becomes extreme.
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Since S3 buckets can now mount to EC2 instances (reference: August 2023 blog post) and S3 costs are ~10X cheaper than EFS, as part of this data retention work perhaps we should also look into what it would take to move to S3 storage (and discuss any features that would not be available with this migration)?


## Persistent Data locations
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## Persistent Data locations
## Persistent Data Locations


Each user has access to 2 locations: `/home/{user}` and `/shared/`
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Within jupyterhub `/home/{user}` the user always sees `/home/jovyan`, but is stored in EFS as their GitHub
username.
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## Known cache file cleanup
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## Known cache file cleanup
## Known Cache File Cleanup


We should be able to safely remove the following:
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- `/home/{user}/.cache`
- `nwb_cache`
- Yarn Cache
- `__pycache__`
- pip cache
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In case user is still active -- I think it would be useful to report to the long running users, after reaching some threshold on any of those folders (e.g. 50MB) asking to clean them up.

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@kabilar kabilar Sep 17, 2024

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Hi @asmacdo, should we add a separate point here about monitoring and reporting the quotas of cache directories for active users?



## Determining Last Access

EFS does not store metadata for the last access of the data. (Though they must track somehow to move
to `Infrequent Access`)
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Alternatives:
- use the [jupyterhub REST API](https://jupyterhub.readthedocs.io/en/stable/reference/rest-api.html#operation/get-users) check when user last used/logged in to hub.
- dandiarchive login information

## Automated Data Audit

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@kabilar kabilar Sep 17, 2024

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At an interval of 7 days:
- Calculate home directory disk usage

At some interval (30 days with no login?):
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At some interval (30 days with no login?):
At an interval of 30 days with no login to JupyterHub:

- find files larger than 1 (?) GB and mtime > 30 (?) days -- get total size and count
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- find _pycache_ and nwb-cache folders and pip cache and mtime > 30? days -- total sizes and list of them

Notify user if:
- total du exceeds some threshold (e.g. 100G)
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- total du exceeds some threshold (e.g. 100G)
- total home directory disk usage exceeds 1 TB

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I suggested a quota of 1 TB for home directories as many datasets are getting to be quite large. This would provide temporary, high-capacity storage, but hopefully users won't get anywhere near this threshold. This would cost $300/user/month for standard EFS, and $23/user/month if we move to Standard S3.

If we implement a scratch directory, then perhaps the home directory can have a much smaller quota.

- total outdated caches size exceeds some threshold (e.g. 1G)
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- total outdated caches size exceeds some threshold (e.g. 1G)
- total outdated caches size exceeds 1 GB

- prior notification was sent more than a week ago

Notification information:
- large file list
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- large file list
- summarized audit data (total size and count for each of the above thresholds)
- large file list

- summarized data retention policy
- Notice number
- request to cleanup
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meanwhile it might be worth creating a simple data record schema to store those records as well so they could be reused by the tools to assemble higher level stats etc.


### Non-response cleanup

If a user has not logged in for 60 days (30 days initial + 30 days following audit), send a warning:
`In 10 days the following files will be cleaned up`

If the user has not logged in for 70 days (30 initial + 30 after audit + 10 warning):
`The following files were removed`

Reset timer.