[LUDOC-223] Is the "FID-in-dirent" feature (ie. tunefs -O dirdata) is backwards compatible with 1.8.9 clients?

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Environment: Lustre 2.1.5 MDS/OSS; Lustre 1.8.9 Clients
• Severity: 2
• Assignee: Jodi Levi (Inactive)
• Reporter: Oz Rentas

Description

Yale just recently upgrade their MDS and OSS servers running 2.1.5 (upgraded from 1.8.9). However, the client are still running 1.8.9.

Although it has been stated 1.6+ clients understand the new FID format, the 2.x lustre operations manual at hpdd-intel doesn't explicitly say it will work with older clients. They would like clarification on if the "FID-in-dirent" feature (ie. tunefs -O dirdata) is backwards compatible with 1.8.9 clients ?

Also, is there high risk involved enabling "dirdata" when running old 1.8.9 clients ? Any opinions if there is benefit in using this flag ?