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OLCF users have many options for data storage. Each user has multiple user-affiliated storage spaces, and each project has multiple project-affiliated storage spaces where data can be shared for collaboration. Below we give an overview and explain where each storage area is mounted.
AlpineTDS IBM Spectrum Scale Filesystem
Currently Summit mounts a POSIX-based IBM Spectrum Scale parallel filesystem called AlpineTDS. It is the initial test and development system that will be followed by the full production Spectrum Scale filesystem called Alpine. Early Summit users are expected to do their production I/O using AlpineTDS until the full Alpine is deployed. AlpineTDS has an approximate capacity of 3 PB and an approximate maximum speed of 30 GB/s. AlpineTDS will be removed from production and reformatted after the Alpine filesystem is available for production. Alpine’s maximum capacity will be 250 PB. The maximum performance of the final production system will be about 2.5 TB/s for sequential I/O and 2.2 TB/s for random I/O.
For best performance on the IBM Spectrum Scale filesystem, use large pagealigned I/O and asynchronous reads and writes. The filesystem blocksize is 16MB, The minimum fragment size is 16K so when a file under 16K is stored, it will still use 16K of the disk. Files writes of 16 MB or larger, will achieve better performance. All files are striped across LUNs which are distributed across all IO servers.
Other OLCF Storage Systems
The High Performance Storage System (HPSS) at the OLCF provides longer-term storage for the large amounts of data created on the OLCF compute systems. The HPSS is accessible from all OLCF Filesystems through utilities called HSI and HTAR. For more information on using HSI or HTAR, see the HPSS Best Practices documentation.
OLCF also has a Network File System, referred to as NFS, and Lustre filesystems called Atlas. Summit does not mount Lustre. However, during the early use of Summit, users may need to use Lustre in a multi-stage process with HPSS for larger data transfer with AlpineTDS. To learn more about this please see Data Transfer and Summit section below.
The following shows the availability of each of the filesystems on primary OLCF clusters and supercomputers.
|Area||Summit||Titan||Data Transfer Nodes||Rhea||Eos|
|Atlas Lustre Filesystem||yes||yes||yes||yes|
|AlpineTDS Spectrum Scale Filesystem||yes|
|NFS Network Filesystem||yes||yes||yes||yes||yes|
The storage area to use in any given situation depends upon the activity you wish to carry out.
Each user has a User Home area on a Network File System (NFS) and a User Archive area on the archival High Performance Storage System (HPSS). These user storage areas are intended to house user-specific files.
Each project has a Project Home area on NFS, multiple Project Work areas on Lustre and Spectrum Scale, and a Project Archive area on HPSS. These project storage areas are intended to house project-centric files.
We have defined several areas as listed below by function:
- User Home: Long-term data for routine access that is unrelated to a project.
- User Archive: Long-term data for archival access that is unrelated to a project.
- Project Home: Long-term project data for routine access that’s shared with other project members.
- Member Work: Short-term user data for fast, batch-job access that is not shared with other project members. There are versions of this on both the Atlas Lustre filesystem and the AlpineTDS Spectrum Scale filesystem.
- Project Work: Short-term project data for fast, batch-job access that’s shared with other project members. There are versions of this on both the Atlas Lustre filesystem and the AlpineTDS Spectrum Scale filesystem.
- World Work: Short-term project data for fast, batch-job access that’s shared with OLCF users outside your project. There are versions of this on both the Atlas Lustre filesystem and the AlpineTDS Spectrum Scale filesystem.
- Project Archive: Long-term project data for archival access that’s shared with other project members.
A brief description of each area and basic guidelines to follow are provided in the table below:
||Lustre||700||no||14 days||10 TB|
||Lustre||770||no||90 days||100 TB|
On Titan, Rhea, and Eos, paths to the various project-centric work storage areas are simplified by the use of environment variables that point to the proper directory on a per-user basis:
- Member Work Directory:
- Project Work Directory:
- World Work Directory:
These environment variables are not set on Summit or the data transfer nodes.
To keep the Lustre and Spectrum Scale filesytems exceptionally performant, untouched files in the project and user areas are purged at the intervals shown in the table above. Please make sure that valuable data is moved off of these systems regularly. See HPSS Best Practices for information about using the HSI and HTAR utilities to archive data on HPSS.
Backups for Files on NFS
Online backups are performed at regular intervals for your files in project home and user home. Hourly backups for the past 24 hours, daily backups for the last 7 days, and 1 weekly backup are available. The backup directories are named
daily.* , and
* is the date/time stamp of the backup. For example,
hourly.2016-12-01-0905 is an hourly backup made on December 1, 2016 at 9:05 AM.
The backups are accessed via the
.snapshot subdirectory. You may list your available hourly/daily/weekly backups by doing “
ls .snapshot”. The
.snapshot feature is available in any subdirectory of your home directory and will show the online backup of that subdirectory. In other words, you don’t have to start at
/ccs/home/$USER and navigate the full directory structure; if you’re in a /ccs/home subdirectory several “levels” deep, an “
ls .snapshot” will access the available backups of that subdirectory.
To retrieve a backup, simply copy it into your desired destination with the
At the completion of a project or at the end of a member’s association with the project, data will be retained for 90 days, except in areas that are purged, in that case the data will be retained according the purge policy.
A more detailed description of each storage area is given below.
User-Centric Data Storage
The following table summarizes user-centric storage areas available on OLCF resources and lists relevant polices.
||NFS||User-controlled||10 GB||Yes||No||90 days|
||HPSS||User-controlled||2 TB ||No||No||90 days|
User Home Directories (NFS)
The environment variable
$HOME will always point to your current home directory. It is recommended, where possible, that you use this variable to reference your home directory. In cases in which using
$HOME is not feasible, it is recommended that you use
Users should note that since this is an NFS-mounted filesystem, its performance will not be as high as other filesystems.
User Home QuotasQuotas are enforced on user home directories. To request an increased quota, contact the OLCF User Assistance Center. To view your current quota and usage, use the
$ quota -Qs Disk quotas for user usrid (uid 12345): Filesystem blocks quota limit grace files quota limit grace nccsfiler1a.ccs.ornl.gov:/vol/home 4858M 5000M 5000M 29379 4295m 4295m
User Home Permissions
The default permissions for user home directories are
0750 (full access to the user, read and execute for the group). Users have the ability to change permissions on their home directories, although it is recommended that permissions be set to as restrictive as possible (without interfering with your work).
User Website Directory
Users interested in sharing files publicly via the World Wide Web can request a user website directory be created for their account. User website directories (
~/www) have a 5GB storage quota and allow access to files at
user is your userid). If you are interested in having a user website directory created, please contact the User Assistance Center at email@example.com.
User Archive Directories (HPSS)
The High Performance Storage System (HPSS) at the OLCF provides longer-term storage for the large amounts of data created on the OLCF compute systems. The mass storage facility consists of tape and disk storage components, servers, and the HPSS software. After data is uploaded, it persists on disk for some period of time. The length of its life on disk is determined by how full the disk caches become. When data is migrated to tape, it is done so in a first-in, first-out fashion.
User archive areas on HPSS are intended for storage of data not immediately needed in either User Home directories (NFS) or User Work directories (Lustre®). User Archive directories should not be used to store project-related data. Rather, Project Archive directories should be used for project data.
User archive directories are located at
User Archive Access
Each OLCF user receives an HPSS account automatically. Users can transfer data to HPSS from any OLCF system using the HSI or HTAR utilities. For more information on using HSI or HTAR, see the HPSS Best Practices section.
User Archive Accounting
Each file and directory on HPSS is associated with an HPSS storage allocation. For information on HPSS storage allocations, please visit the HPSS Archive Accounting section.
For information on usage and best practices for HPSS, please see the HPSS Best Practices documentation.
Project-Centric Data Storage
Project directories provide members of a project with a common place to store code, data, and other files related to their project.
Project Home Directories (NFS)
Projects are provided with a Project Home storage area in the NFS-mounted filesystem. This area is intended for storage of data, code, and other files that are of interest to all members of a project. Since Project Home is an NFS-mounted filesystem, its performance will not be as high as other filesystems.
Project Home Path
Project Home area is accessible at
abc123 is your project ID).
Project Home Quotas
To check your project’s current usage, run
df -h /ccs/proj/abc123 (where
abc123 is your project ID). Quotas are enforced on project home directories. The current limit is shown in the table above.
Project Home Permissions
The default permissions for project home directories are
0770 (full access to the user and group). The directory is owned by root and the group includes the project’s group members. All members of a project should also be members of that group-specific project. For example, all members of project “ABC123” should be members of the “abc123” UNIX group.
Three Project Work Areas to Facilitate Collaboration
To facilitate collaboration among researchers, the OLCF provides (3) distinct types of project-centric work storage areas: Member Work directories, Project Work directories, and World Work directories. Each directory should be used for storing files generated by computationally-intensive HPC jobs related to a project.
||Lustre||700||no||14 days||10 TB|
||Spectrum Scale||700||no||90 days||TBD|
||Lustre||770||no||90 days||100 TB|
||Spectrum Scale||770||no||90 days||TBD|
||Spectrum Scale||775||no||90 days||TBD|
The difference between the three lies in the accessibility of the data to project members and to researchers outside of the project. Member Work directories are accessible only by an individual project member by default. Project Work directories are accessible by all project members. World Work directories are readable by any user on the system.
UNIX Permissions on each project-centric work storage area differ according to the area’s intended collaborative use. Under this setup, the process of sharing data with other researchers amounts to simply ensuring that the data resides in the proper work directory.
- Member Work Directory:
- Project Work Directory:
- World Work Directory:
For example, if you have data that must be restricted only to yourself, keep them in your Member Work directory for that project (and leave the default permissions unchanged). If you have data that you intend to share with researchers within your project, keep them in the project’s Project Work directory. If you have data that you intend to share with researchers outside of a project, keep them in the project’s World Work directory.
Member Work, Project Work, and World Work directories are not backed up. Project members are responsible for backing up these files, either to Project Archive areas (HPSS) or to an off-site location.
Project Archive Directories
Projects are also allocated project-specific archival space on the High Performance Storage System (HPSS). The default quota is shown on the table above. If a higher quota is needed, contact the User Assistance Center.
The Project Archive space on HPSS is intended for storage of data not immediately needed in either Project Home (NFS) areas nor Project Work (AlpineTDS) areas, and to serve as a location to store backup copies of project-related files.
Project Archive Path
The project archive directories are located at
pjt000 is your Project ID).
Project Archive Access
Project Archive directories may only be accessed via utilities called HSI and HTAR. For more information on using HSI or HTAR, see the HPSS Best Practices section.
Data Transfer and Summit
Early Summit users will have access to a 3 PB GPFS file system call AlpineTDS. Because this file system is shared by all users, and due to its limited size, it is important to transfer your data off of AlpineTDS whenever possible. Another reason it is important to regularly transfer your data off of AlpineTDS is that the system is still under development, so it is possible your data could be lost without warning.
AlpineTDS will not be mounted on OLCF’s data transfer nodes, so transfers will be staged on the Summit login nodes. However, when the full Alpine file system goes into production, it will be mounted on the data transfer nodes as well as Summit, and the data transfer process will become enabled by tools like Globus.
The following sections will outline the current options for transferring data to and from AlpineTDS.
For local data transfers (e.g. from AlpineTDS to Atlas), users have two options depending on the size of the data. For small data transfers, users can first copy data (via the
cp command) from AlpineTDS to the NFS storage area (i.e. home
/ccs/home/userid/ or project space
/ccs/proj/), and then from their NFS directory to Atlas (/lustre/atlas). Because the NFS storage areas have a 50 GB quota, such transfers must be less than 50 GB.
If larger data must be moved between AlpineTDS and Atlas, it can be passed through HPSS. For example, if your data is initially located in
/lustre/atlas/proj-shared/[projid] and you want to move it to
Log in to
cd /lustre/atlas/proj-shared/[projid] htar -cvf mylargefiles.tar mylargefiles
cd /gpfs/alpinetds/scratch/[projid] htar -xvf mylargefiles.tar
Below is a screencast showing the process of transferring data from AlpineTDS to Atlas.
Remote Transfers with AlpineTDS
rsync are available on Summit for small remote transfers.
For larger remote transfers with AlpineTDS, we recommend staging the data through Atlas and using Globus to do the remote transfer. In this case, HPSS can be used as a pass-through between Atlas and AlpineTDS as mentioned above.
Please see the Titan User Guide’s Remote Transfers section for additional options (and more detailed information) about how to transfer data between Atlas and systems located outside OLCF.
HPSS Best Practices
Currently HSI and HTAR are offered for archiving data into HPSS or retrieving data from the HPSS archive.
For optimal transfer performance we recommend sending file of 768 GB or larger to HPSS. The minimum file size that we recommend sending is 512 MB. HPSS will handle files between 0K and 512 MB, but write and read performance will be negatively affected. For files smaller than 512 MB we recommend bundling them with HTAR to achieve an archive file of at least 512 MB.
When retrieving data from a tar archive larger than 1 TB, we recommend that you pull only the files that you need rather than the full archive. Examples of this will be give in the htar section below.
Issuing the command
hsi will start HSI in interactive mode. Alternatively, you can use:
hsi [options] command(s)
…to execute a set of HSI commands and then return.
To list you files on the HPSS, you might use:
hsi commands are similar to
ftp commands. For example,
hsi get and
hsi put are used to retrieve and store individual files, and
hsi mget and
hsi mput can be used to retrieve multiple files.
To send a file to HPSS, you might use:
hsi put a.out
To put a file in a pre-existing directory on hpss:
hsi “cd MyHpssDir; put a.out”
To retrieve one, you might use:
hsi get /proj/projectid/a.out
Here is a list of commonly used hsi commands.
|cd||Change current directory|
|get, mget||Copy one or more HPSS-resident files to local files|
|cget||Conditional get – get the file only if it doesn’t already exist|
|cp||Copy a file within HPSS|
|rm mdelete||Remove one or more files from HPSS|
|ls||List a directory|
|put, mput||Copy one or more local files to HPSS|
|cput||Conditional put – copy the file into HPSS unless it is already there|
|pwd||Print current directory|
|mv||Rename an HPSS file|
|mkdir||Create an HPSS directory|
|rmdir||Delete an HPSS directory|
Additional HSI Documentation
There is interactive documentation on the
hsi command available by running:
htar command provides an interface very similar to the traditional
tar command found on UNIX systems. It is used as a command-line interface. The basic syntax of
As with the standard Unix
tar utility the
-t options, respectively, function to create, extract, and list tar archive files. The
-K option verifies an existing tarfile in HPSS and the
-X option can be used to re-create the index file for an existing archive.
For example, to store all files in the directory
dir1 to a file named
allfiles.tar on HPSS, use the command:
htar -cvf allfiles.tar dir1/*
To retrieve these files:
htar -xvf allfiles.tar
htar will overwrite files of the same name in the target directory.
When possible, extract only the files you need from large archives.
To display the names of the files in the
project1.tar archive file within the HPSS home directory:
htar -vtf project1.tar
To extract only one file,
executable.out, from the
project1 directory in the Archive file called
htar -xm -f project1.tar project1/ executable.out
To extract all files from the
project1/src directory in the archive file called
project1.tar, and use the time of extraction as the modification time, use the following command:
htar -xm -f project1.tar project1/src
htar utility has several limitations.
You cannot add or append files to an existing archive.
File Path Length
File path names within an
htar archive of the form prefix/name are limited to 154 characters for the prefix and 99 characters for the file name. Link names cannot exceed 99 characters.
There are limits to the size and number of files that can be placed in an HTAR archive.
|Individual File Size Maximum||68GB, due to POSIX limit|
|Maximum Number of Files per Archive||1 million|
For example, when attempting to HTAR a directory with one member file larger that 64GB, the following error message will appear:
[titan-ext1]$htar -cvf hpss_test.tar hpss_test/ INFO: File too large for htar to handle: hpss_test/75GB.dat (75161927680 bytes) ERROR: 1 oversize member files found - please correct and retry ERROR: [FATAL] error(s) generating filename list HTAR: HTAR FAILED