# EOS-drive for Windows: Architecture and file transferring system

- Institution: CERN
- Department: HEP Computing
- Speaker: Ivan Arizanovic
- Year: 2023
- Language: English
- Subjects: Computer science
- Source: [CERN](https://videos.cern.ch/record/3003125)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Tweens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

EOS-drive is part of the EOS Windows Native Client package, it mounts the EOS filesystem as a Windows disk drive by which Windows applications interact with the EOS filesystem.

EOS-drive communicates with Windows applications through the user-mode Dokan library and kernel-mode Dokan driver. File operation requests from applications (e.g., CreateFile, ReadFile, WriteFile...) are sent to the Dokan driver, which is then forwarded to the Dokan library and subsequently to the EOS-drive. The results of this routine are sent back to the Windows application as a response to the operation request. The Dokan file system driver and library therefore acts as a proxy between Windows applications and the EOS-drive.

To collect data that should be sent to the Windows application as a response to an operation request, EOS-drive communicates with the EOS cluster through HTTPS protocol. EOS-drive uses the cURL library for file transferring and gRPC for metadata requests.

WriteFile and ReadFile operations are used for file transferring. Windows applications requests a process over chunks (data fragments) by providing offset and chunk size to the EOS-drive. Then, EOS-drive is made to serve Windows applications by performing WriteFile or ReadFile operations over specified chunks.

There are three mechanisms of file transferring in EOS-drive, these are: transfer chunk by chunk, transfer with the EOS-drive buffer, and single-session transfer.

Transferring chunk by chunk means that each requested chunk by the Windows applications will be uploaded/downloaded in a separate session. This method is the slowest but can be realized in any case.

Transferring with an EOS-drive buffer can be done in three different scenarios. In case of upload, EOS-drive buffers some of the chunks received from the Windows driver, sorts them if needed, and uploads them together per second. With regards to downloading "small" files, instead of downloading the requested chunk, EOS-drive will download the whole…

## Lectures

1. [EOS-drive for Windows: Architecture and file transferring system](https://invisiblenetwork.ai/learn/cern/3003125/2784c31f5274), 9 min (CERN's player)