COLD
COLD data stores are meant for medium term data storage (months to a few years) and are configured for robustness rather than performance. The characteristics of COLD data stores are
- Optimized for high capacity
- Optimized for robustness rather than performance
- Has a quota
- Has snapshots
- Has NO backups
The COLD filesystems have medium performance. The COLD data stores for each kind of project are:
| Kind of Project | Name | Media | Capacity | Filesystem |
|---|---|---|---|---|
| NHR | Ceph HDD Cold | HDD with metadata on SSD | 21 PiB (shared) | CephFS |
Info
Legend for the tags in the Capacity column:
(shared): They share capacity with other data stores. For example, NHR COLD and SCC Project data stores are on the same storage system.
The paths for the data store directories and their symlinks in the Project Map for each project are:
| Project Data Store | Path | Project Map symlink |
|---|---|---|
| Ceph HDD Cold | /mnt/ceph-hdd/cold/PROJECT | dir.ceph-hdd |
Snapshots
If you accidentally deleted or overwrote something in your COLD directory and want to restore an earlier version of the affected files, it is not generally necessary to write a ticket.
The COLD filesystems save regular snapshots that are kept for a short period (currently 30 days of daily snapshots).
These snapshots can be accessed for any directory by entering the hidden .snapshot directory by cd .snapshot.
Unlike backups, they do not protect against the loss of the entire filesystem.
Info
The .snapshot directories are “hidden” on a deep level, so that they don’t even show up with ls -a, and thus autocomplete on the command line does not work for them.
They are implemented this way on CephFS filesystems, so they can be accessed everywhere, for every (sub-)directory, and are not included when copying or moving directories to another location.