HOME
Every user gets a HOME directory.
Its path is always stored in the environmental variable $HOME and most shells will expand ~ into it.
The directory will be HOME_BASE/ACADEMIC_CLOUD_USERNAME/USER for members of projects in the HPC Project Portal and HOME_BASE/USER otherwise (e.g. legacy HLRN accounts), where HOME_BASE is one of the base directories for home directories (there is more than one and they may change in the future).
The base directory shown by POSIX commands (like getent passwd) or in the environment variables can be a symbolic link (e.g. /user), which points to the actual base directory on the data store (e.g. /mnt/vast-nhr/home), or another link farm (/mnt/vast-orga) which only contains symlinks to the real home directories.
The HOME directory is meant for a user’s:
- configuration files
- source code
- self-built software
The HOME storage systems have the following characteristics:
- Optimized for a high number of files rather than capacity
- Optimized for robustness rather than performance
- Has limited disk space per user
- Is regularly backed up to tape (most also have snapshots, see below)
- Has a quota
The HOME filesystems have slow-medium to medium performance. The HOME directories for each kind of user are given in the table below.
| Kind of User | Media | Capacity | Filesystem |
|---|---|---|---|
| NHR | SSD | 1.15 PiB (shared)(comp)(dedup) | VAST exported via NFS |
| SCC (Project Portal users) | SSD | 1.15 PiB (shared)(comp)(dedup) | VAST exported via NFS |
| SCC (legacy) | HDD | 10.5 PiB | Stornext exported directly and via NFS |
| KISSKI | SSD | 1.15 PiB (shared)(comp)(dedup) | VAST exported via NFS |
| REACT | SSD | 1.15 PiB (shared)(comp)(dedup) | VAST exported via NFS |
Legend for the tags in the Capcity column:
(shared): They share capacity with other data stores. For example, NHR HOME and Project data stores are on the same storage system.
(comp): Use live compression to increase effective capacity, though this comes at the expense of some CPU time to compress and decompress.
(dedup): Use deduplication to increase effective capacity.
Legacy SCC users have their HOME directories on the GWDG Unix HOME filesystem, which is only accessible from SCC Legacy nodes. See Cluster Storage Map for more information.
Snapshots
If you accidentally deleted or overwrote something in your home directory and want to restore an earlier version of the affected files, it is not always necessary to write a ticket.
Most of our home filesystems save regular snapshots that are kept for a short period (between a few days up to 3-4 weeks).
These snapshots are either found at HOME_BASE/.snapshots, or can be accessed for any directory by typing cd .snapshot (on Vast).