Limited symbolic link support

•sockets

•pipes

Consequently, these files cannot be created on an HSM file system.

Directories with sticky bit not supported

The FSE implementation does not support handling of “sticky directories”, that is, directories with the sticky bit set. Such directories cannot be copied to HSM file systems and the sticky bit cannot be applied to existing directories on HSM file systems.

The sticky bit is represented with the attribute character t or T in the output of the ls command, as shown in this example:

-rwxrwxrwx	1	root	root	16932	Nov 26		08:02 file
drwxrwxrwx	2	root	root	4096	Nov 26		09:38 non_sticky_dir
drwxrwxrwt	2	root	root	4096	Nov	26	08:26	sticky_dir
drwxrwxrwT	2	root	root	4096	Nov	26	09:36	sticky_dir_2

If you try to copy a sticky directory to an HSM file system or try to modify the attributes of an existing directory on an HSM file system to include the sticky bit, the cp and chmod commands fail with the following errors:

cp: cannot create directory `/mnt/hsmfs01/test': Operation not permitted

chmod: changing permissions of `/mnt/hsmfs01/test': Operation not permitted

The reason for this limitation is Ext3 extended attributes, which are used by the FSE implementation, but cannot be added to sticky directories.

Even though an HSM file system allows symbolic links to be created on it and permits other file operations on these links, they are never migrated to FSE media. Since they occupy very little disk space and do not obstruct normal HSM file system operation, this is not a drawback.

The problem arises if the HSM file system is completely destroyed and has to be recovered from FSE media. In this case, the recovery of the HSM file system is not complete because of the missing symbolic links on the FSE media.

File size limitation

On Linux hosts, the maximum size of a file created on an HSM file system is limited by the underlying Ext3 file system size limit. In the current version of the Linux kernel (2.4), this limit is two terabytes (2 TB).

Generally, the maximum size of a file that can be migrated from an HSM file system to FSE media is limited by the size of disk buffer and by the amount of free space on all FSE media in the respective FSE media pool. Files that are larger than the disk buffer cannot be migrated, and therefore, they permanently occupy space on the HSM file system.

Append-only and immutable files cannot be released

Files on an HSM file system with the append-only or immutable status (set by the appropriate special file attributes) cannot be released. They are migrated in the same way as all other files but are not released. Consequently, these files are not recalled and permanently occupy space on the HSM file system.

Pathname length limitation

An FSE implementation cannot gain control of files whose full pathname exceeds 4096 characters. A full pathname consists of the absolute path of a file (including path separators—slashes) and the name of the file. An absolute path is the path from the root directory of the root file system. Files whose pathnames are too long remain dirty forever; they are not migrated to FSE media and therefore cannot be released from the HSM file system.

hp StorageWorks File System Extender Release Notes 21

File System Extender (FSE) specifications

HP File System Extender (FSE) is a sophisticated solution designed to optimize data storage management for enterprises that deal with large volumes of unstructured data. This technology addresses the challenges of data growth and the need for effective data retention strategies, enabling organizations to store and manage their information more efficiently.

One of the main features of HP FSE is its ability to intelligently migrate data between primary and secondary storage. By utilizing policies that determine when to move infrequently accessed files to lower-cost storage environments, FSE helps reduce the strain on primary storage systems and saves on costs associated with high-performance storage solutions. This tiered approach to data management ensures that organizations can access the data they need quickly while still maintaining an efficient overall storage architecture.

Another notable characteristic of HP FSE is its seamless integration with existing storage infrastructures. The solution works with a variety of storage systems, allowing organizations to utilize their current investments without the need for significant changes to their infrastructure. This interoperability is powered by advanced technologies that facilitate data migration and retrieval, ensuring a smooth transition for organizations looking to optimize their storage strategies.

Additionally, HP FSE is equipped with robust reporting and analytics capabilities. This functionality provides organizations with insights into their storage usage, helping them understand data patterns and optimize their storage environments accordingly. By having visibility into which files are accessed most frequently and which are rarely used, organizations can make informed decisions on data retention policies and storage management.

Security is paramount in data management, and HP FSE addresses this concern by implementing advanced data protection features. This includes data encryption, secure access controls, and compliance with industry regulations, ensuring that sensitive information is safeguarded throughout its lifecycle.

Overall, HP File System Extender is a comprehensive data storage solution that combines intelligent data management, seamless integration, insightful analytics, and robust security features. By leveraging these capabilities, organizations can efficiently manage their unstructured data, lower costs, and enhance operational efficiency, making it an invaluable tool in today’s data-driven landscape.