# dcache-cta

**Repository Path**: mirrors_mcmilk/dcache-cta

## Basic Information

- **Project Name**: dcache-cta
- **Description**: dCache driver for CTA
- **Primary Language**: Unknown
- **License**: AGPL-3.0
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2025-06-05
- **Last Updated**: 2026-10-11

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# dCache Nearline Storage Driver for CTA

<img src=".assets/cta+dcache.png" height="165" width="200">

This is nearline storage plugin for dCache.

[![DOI](https://zenodo.org/badge/415029713.svg)](https://zenodo.org/badge/latestdoi/415029713)

## Building from source

### Tar

To compile the plugin, run:

    mvn package

This produces a tarball in the `target` directory containing the plugin.

### RPM

```
mvn clean package
mkdir -p rpmbuild/{BUILD,RPMS,SOURCES,SPECS,SRPMS}
cp target/dcache-cta*.tar.gz rpmbuild/SOURCES
rpmbuild -ba --define "_topdir `pwd`/rpmbuild" target/SPECS/dcache-cta.spec
```

## Using the plugin with dCache

To use this plugin with dCache, place the directory containing this
file in /usr/local/share/dcache/plugins/ on a dCache pool. Restart
the pool to load the plugin.

To verify that the plugin is loaded, navigate to the pool in the dCache admin
shell and issue the command:

    hsm show providers

The plugin should be listed as **dcache-cta**.

To activate the plugin, create an HSM instance using:

    hsm create osm name dcache-cta [-key=value]...

example:

    hsm create osm cta dcache-cta -cta-user=userA \
         -cta-group=groupA -cta-instance-name=instanceA \
         -cta-frontend-addr=cta-forntend-host1:17017,cta-forntend-host2:17017 \
         -cta-use-tls=true \
         -io-endpoint=a.b.c.d -io-port=1094

The dCache files stored in CTA will have hsm uri in form
```
<hsmType>://<hsmName>/<pnfsid>?archiveid=<id>
```
Where `id` represents the CTA internal `archiveId`

for example:
```
osm://cta/00001D43C0C086CA459298C634D67F68AB6B?archiveid=8402
```

In the CTA catalog the dCache's `pnfsid`s are referenced as `disk_file_id` field:

```
db => select * from archive_file where disk_file_id = '00001D43C0C086CA459298C634D67F68AB6B';
-[ RECORD 1 ]-------+-------------------------------------
archive_file_id     | 8402
disk_instance_name  | instanceA
disk_file_id        | 00001D43C0C086CA459298C634D67F68AB6B
disk_file_uid       | 1
disk_file_gid       | 1
size_in_bytes       | 10482
checksum_blob       | \x0a08080112043309f498
checksum_adler32    | 2566129971
storage_class_id    | 81
creation_time       | 1635150624
reconciliation_time | 1635150624
is_deleted          | 0
collocation_hint    |
```

> NOTE: dCache-CTA driver doesn't preserve file's ownership, thus values of `uid` and `gid` fields
> contain arbitrary values.

## dCache pool configuration

As CTA has its own scheduler and flush/restore queue the dCache pools should be configured to
submit as much request as possible. Thus grouping and collecting request on the pool side should
be disabled:

```
queue define class -expire=0 -pending=0 -total=0 -open <hsmType> *
```

### The available configuration options:

| Name                     | Description                                                                     | required | default    |
|:-------------------------|:--------------------------------------------------------------------------------|---------:|------------|
| cta-instance-name        | The dCache instance name configured in CTA                                      |      yes | -          |
| cta-frontend-addr        | A comma separated list of  CTA `cta-dcache` endpoints                           |      yes | -          |
| cta-user                 | The dCache instance associated user in CTA                                      |      yes | -          |
| cta-group                | The dCache instance associated group in CTA                                     |      yes | -          |
| cta-ca-chain             | The path to CA root chain for use with TLS                                      |       no | -          |
| cta-use-tls              | A switch (none/tls/mtls or true/false) to enable TLS for CTA control connection |       no | `none`     |
| cta-tls-cert             | The path to TLS certificate for use with mTLS                                   |       no | -          |
| cta-tls-key              | The path to TLS key for use with mTLS                                           |       no | -          |
| cta-frontend-timeout     | How long dCache waits in seconds for CTA frontend to reply                      |       no | 30         |
| io-endpoint              | The hostname or IP offered by dCache for IO by CTA                              |       no | `hostname` |
| io-port                  | The TCP port offered by dCache for IO by CTA                                    |       no | -          |
| use-dio                  | Use Direct-I/O                                                                  |       no | `false`    |
| restore-success-on-close | **obsolete**                                                                    |        - | -          |

### Load balancing and failover

If multiple `cta-frontend-addr` are provided, the driver will try to connect to all endpoints and use `round-robin`
strategy to distribute the requests. If TLS is used, then all endpoints names should be present in SAN field of the
certificate.

## Compatibility with CTA

The driver is compatible with all dCache versions staring 7.2. The compatibility CTA versions are:

| CTA Version              | dcache-cta version |
|:-------------------------|:-------------------|
| 5.7.12 - 5.10.xx         | 0.6.0 - 0.14.0     |
| 5.11.0 - xxx             | 0.15.0             |


## External Contribution Formalities

Each externally submitted patch must have a "Signed-off-by" line.  Patches without
this line will not be accepted.

The sign-off is a simple line at the end of the explanation for the
patch, which certifies that you wrote it or otherwise have the right to
pass it on as an open-source patch.  The rules are pretty simple: if you
can certify the below:

```

    Developer's Certificate of Origin 1.1

    By making a contribution to this project, I certify that:

    (a) The contribution was created in whole or in part by me and I
         have the right to submit it under the open source license
         indicated in the file; or

    (b) The contribution is based upon previous work that, to the best
        of my knowledge, is covered under an appropriate open source
        license and I have the right under that license to submit that
        work with modifications, whether created in whole or in part
        by me, under the same open source license (unless I am
        permitted to submit under a different license), as indicated
        in the file; or

    (c) The contribution was provided directly to me by some other
        person who certified (a), (b) or (c) and I have not modified
        it.

    (d) I understand and agree that this project and the contribution
        are public and that a record of the contribution (including all
        personal information I submit with it, including my sign-off) is
        maintained indefinitely and may be redistributed consistent with
        this project or the open source license(s) involved.

```
then you just add a line saying ( git commit -s )

    Signed-off-by: Random J Developer <random@developer.example.org>

using your real name (sorry, no pseudonyms or anonymous contributions.)


## Acknowledgements

This driver is based and inspired by `cta-communicator` by _Lea Morschel_ and  [`sapphire`](https://github.com/dCache/sapphire) by _Svenja Meyer_