NHR NHR@ZIB is operating at each site 3 central storage systems with their global file systems:
| File System | Capacity | Storage Technology and Function |
|---|---|---|
| HOME | 340 TiB | IBM Spectrum Scale file system, exported via NFS to compute and login nodes
|
| WORK | Lise: 10 PiB | DDN ExaScaler with Lustre parallel file system |
| PERM | Tape archive with multiple petabyte capacity with additional harddisk caches |
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- All nodes of the partition standard96:ssd have local SSDs for temporary data at
$LOCAL_TMPDIR(2 TB per node). For more details refer to Special Filesystems.
LIFETIME
In general, we store all data for an extra year after the end of a test account/project. If not extended, the standard term of test account/project is one year.
HOME
Each user holds one HOME directory:
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The home filesystem and /sw are mounted via NFS, so performance is medium. We take daily snapshots of the filesystem, which can be used to restore a former state of a file or directory. These snapshots can be accessed through the path /home/.snapshots or /sw/.snapshots. There are additional regular backups to restore the filesystem in case of a catastrophic failure.
WORK
The Lustre based work filesystem /scratch is the main work filesystem for the systems. Each user can distribute data to different directories.
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We provide no backup of this filesystem. The storage system of Emmy Lise provides around 65GiB85GiB/s streaming bandwith and Lise around 85GiB/s during the acceptance test. With higher occupancy, the effective (write) streaming bandwidth is reduced.
The storage system is hard-disk based (with SSDs for metadata), so the best performance can be reached with sequential IO of large files that is aligned to the fullstripe size of the underlying RAID6 (Emmy 1MiB, Lise 16MiB).
If you are accessing a large file (1GiB+) from multiple nodes in parallel, please consider to activate striping of the file with the Lustre command lfs setstripe (specific to this file or for a whole directory, changes apply only for new files, so applying a new striping to an existing file requires a file copy) with a sensible stripe_count (recommendation: Emmy up to 32, Lise up to 8) and a stripe_size, which is a multiple of the RAID6 fullstripe size and matches the IO sizes of your job.
A general recommendation for network filesystems is to keep the number of metadata operations for open and closing files, as well as checks for file existence or changes as low as possible. These operations often become a bottleneck for the IO of your job and on large clusters can easily overload the file servers.
PERM, tape archive
The magnetic tape archive provides additional storage for inactive data to free up space on the WORK or HOME filesystem. It is directly accessible on the login nodes..
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