[LU-13104] Automatically adjust block allocator tuning on ldiskfs file systems

• Type: Improvement
• Resolution: Unresolved
• Priority: Major
• Assignee: WC Triage
• Reporter: Artem Blagodarenko (Inactive)

Description

As part of the allocator improvement work, it has been determined that the default block allocator tuning is not optimal once the file system begins to fill and fragment.

The proposal is to automatically adjust the block allocator tuning parameters.

The targeted parameter here is

 /proc/fs/ldiskfs/<disk>/prealloc_table

Default value is

256 512 1024 2048 4096 8096

But for full disk this table need to be shorter. "256 512 1024" or less.

I don't know exactly there is can be landed for Lustre FS usage. I mentioned this idea during LAD2019 and somebody asked to share the script. Chris Walker wrote the script based on my draft. I have attached it to the issue.