As with most cloud storage systems, when a file is uploaded to BlackPearl we call it an “object”. There are some constraints around how objects are named in BlackPearl due to it often being connected to a tape system that stores data using the open LTFS format.
When you configure BlackPearl, you set up Storage Domain(s), which are collections of tape and/or disk partitions. If the Storage Domain includes tape partition(s), you must specify the “LTFS File Name” option for the Storage Domain. This option specifies how the file is named when it is placed on tape. There are two options for the LTFS File Name:
- Object Name — LTFS file names use the format {bucket name}/{object name}, for example bucket1/video1.mov. Object names must comply with LTFS 2.4 specification file naming rules. The file name must be 255 characters or less. If the tapes are ejected from the BlackPearl gateway and loaded into a non‐BlackPearl tape partition, the file names match the object names. The colon character (:) is not allowed in LTFS file names and therefore not allowed in BlackPearl object names. The slash character (/) is also technically not allowed in LTFS files names; however, in BlackPearl a slash is allowed in the object name and will get translated as a directory in the LTFS file system (e.g. directory1/directory2/video1.mov). The following characters are not recommended in LTFS file names or BlackPearl object names for reasons of cross-platform compatibility: control characters such as carriage return (CR) and line feed (LF), double quotation mark (“), asterisk (*), question mark (?), less than sign (<), greater than sign (>), backslash (\), vertical line (|). Note that per the LTFS specification, “Implementations which claim compliance with version 2.4.0 or later of this specification shall support the percent-encoding of names … in order to avoid issues with the characters listed [above].”
- Object ID — LTFS file names use the format {bucket name}/{object id}, for example bucket1/1fc6f09c‐dd72‐41ea‐8043‐0491ab8a6d82. Object names do not need to comply with LTFS file naming rules. The object names are saved as LTFS extended attributes allowing any third party application to reconstruct all the data including the object names.
When building a BlackPearl client, developers should be prepared for customers to choose either LTFS File Name option, and thus should ensure that object names are LTFS compliant as described in the first option above.