[LU-17365] steady LOD update llog connection

• Type: Improvement
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.16.0
• Labels: llog
• Severity: 3
• Assignee: Mikhail Pershin
• Reporter: Mikhail Pershin

Description

Continue LU-15934 work to further improve stability and revival of MDT-MDT update llog connectivity in stressful environment. Currently in progress the following improvements:

• better filtering of possible llog errors, allow to either recreate update llog if it is damaged or retry reconnect if errors are from network
• handle possible -78 in the same way as -ENOENT, create new llog
• in lod_obd_get_info() try to recreate llog context if it is missing after failed/aborted MDT recovery

Note, that lod_process_config() has code to restore llogs when target is set to active:

 rc = lod_sub_prep_llog(env, lod,
                        sub_tgt->ltd_tgt,
                        sub_tgt->ltd_index);
 sub_tgt->ltd_active = !rc;

I am going to make the same in lod_obd_get_info(). These measures could greatly improve situations with lost mdt-mdt connection and need to restart MDTs

 

Issue Links

• is related to: LU-16159 remove update llog files after recovery abort
• is related to: LU-15934 client refused mount with -EAGAIN because of missing MDT-MDT llog connection