2024 Notable System Changes

After decades in service and having served hundreds of users that have archived over 160 petabytes, HPSS is reaching end of its life and will be decommissioned early in 2025.

Please pay attention to the following key dates as you migrate workloads from the center’s HPSS resource to the new nearline resource, Kronos.

2024 OLCF System Decommissions and Notable Changes

Date	Event
Late July	Kronos available for production use.
August 30	HPSS becomes read-only. To help spread the HPSS migration load, please reach out to help@olcf.ornl.gov to help coordinate your large HPSS data migrations.
January 31, 2025	HPSS decommissioned. ALL REMAINING DATA WILL BE PERMANENTLY DELETED

Late July 2024 - Kronos available for production use

Kronos is expected to be available late July 2024. Updates to the availability schedule will be posted to this site and through the OLCF weekly email.

Kronos Overview

Overview

Kronos is the center’s new nearline storage resource. Kronos is multi-tiered containing both disk and tape. Users will interact with the system’s disk sub-system which leverages IBM Storage Scale (GPFS). Data stored on the disk sub-system will automatically be stored on they system’s tape sub-system. The disk sub-system will provide an initial capacity of 134 PB with the ability to expand as need increases. Kronos is capable of bandwidth of up-to 200 GB/s from the center’s Data Transfer Nodes.

Availability Timeline

Kronos is expected to be available late July 2024.

Access / Data Transfer

Kronos will be mounted on the moderate Data Transfer Nodes, Frontier login nodes, and Andes login nodes. Because the system will be mounted as a filesystem, standard UNIX command and tools can be used to interact with Kronos. The resource will also be accessible through the OLCF DTN endpoint in Globus.

Please note that Kronos will not be mounted on the compute nodes of Frontier or Andes.

Because Kronos is in the moderate security enclave, all projects with allocations to Summit, Frontier, or Andes will receive an allocation on Kronos.

Directory Structure

Kronos will use a directory structure similar to other center-wide storage resources:

Path	Permissions	Owner	Group	Description
/nl/kronos/olcf/<projectID>/proj-shared	755	root	<projectID> UNIX group	Data shared between project members.
/nl/kronos/olcf/<projectID>/users/<userID>	700	<userID>	<projectID> UNIX group	User data, access is limited to user by default, but each user can modify their directory permissions to share with other project members.
/nl/kronos/olcf/<projectID>/world-shared	2775	root	<projectID> UNIX group	Data accessible to others in the OLCF user community

HPSS and Kronos Comparison

Notable comparisons between Kronos and HPSS

Process	HPSS	Kronos
Accessibility	DTNs and login nodes	DTNs and login nodes
Transfer tools	hsi, htar, globus	globus and standard UNIX transfer utilities
File and directory management	hsi	standard UNIX utilities
Data retrieval speeds	Fluctuates based on data location, can see delay if only stored on tape	All data stored on disk providing consistent access experience

August 30, 2024 - HPSS becomes read-only

In preparation for HPSS’s decommission in January 2025, the HPSS will become read-only from all OLCF resources in August 30, 2024.

We highly encourage all teams to start migrating needed data from the HPSS now. If you wait too late in the year to begin the transition, you will run the risk of running out of time to move your data before the system is decommissioned. It is important to note that any data remaining on the HPSS after January 31, 2025, will be unavailable. We expect HPSS periods of access impacts due to the expected volumes of data migrating off of the HPSS. To help spread the HPSS migration load, please reach out to help@olcf.ornl.gov to help coordinate your larger HPSS data migrations.

Data migration

Note

We expect HPSS periods of access impacts due to the expected volumes of data migrating off of the HPSS. To help spread the HPSS migration load, please reach out to help@olcf.ornl.gov to help coordinate your large HPSS data migrations.

Copying data directly from HPSS to Kronos

The hsi utility will provide the best performance and HPSS tape organization. To transfer data from the HPSS to Kronos, the preferred method is to utilize the hsi utility from the DTN. Since the DTN will mount Kronos, hsi transfers can be performed from within a Kronos directory on the DTNs.

Note

You may see longer retrieval times for data stored only on tape than data stored on disk. Please consider physical tape access overhead when planning your data migration. Please reach out to help@olcf.ornl.gov with extended retrieval delay concerns.

Data Deletion

Due to the added overhead of data deletion, we ask that users not delete data from the HPSS.

Globus

The Globus utility is not aware of the underlying HPSS tape storage structure. To help spread the load over the resource’s tape retrieval system, we ask that Globus not be used to migrate data off of the HPSS. Instead, please use the HPSS hsi utility. The HPSS Globus endpoint will be disabled on August 30, 2024 to help ensure efficient migration from HPSS tape.

Warning

The Globus utility is not aware of the underlying HPSS tape storage structure. To help ensure safe and efficient migration of data from tape, the HPSS Globus endpoint will be disabled on August 30, 2024. Instead of Globus, please use the HPSS hsi utility.

HSI Data Lists

The HPSS hsi utility is the preferred tool for HPSS data migration because it is aware of the HPSS tape storage structure. To ensure the most efficient retrieval of data stored on tape, we recommend passing list files to hsi.

• Bad practice Successive hsi get calls

  $ hsi get /hpss/prod/abc123/users/userA/file1
  $ hsi get /hpss/prod/abc123/users/userA/file2
  $ hsi get /hpss/prod/abc123/users/userA/file3
  

• Good practice create a list file & call hsi once

  $ cat getfiles.lst
  get <<EOF
  /hpss/prod/abc123/users/userA/file1
  /hpss/prod/abc123/users/userA/file2
  /hpss/prod/abc123/users/userA/file3
  EOF
  
  $ hsi "in getfiles.lst"
  

January 31, 2025 - HPSS decommissioned

On January 31, 2025, data remaining on the HPSS will no longer be accessible and will be permanently deleted. Following this date, the OLCF will no longer be able to retrieve data remaining on HPSS.

Warning

January 31, 2025, all remaining HPSS data will be PERMANENTLY DELETED. Do not wait to move needed data.