[LU-14141] WBC: Stripe directory not flushed to MDT when it grows large enough

• Type: Technical task
• Resolution: Unresolved
• Priority: Minor
• Assignee: Qian Yingjin
• Reporter: Qian Yingjin

Description

Currently Lustre supports restriping on MDT when a directory is growing big enough.

Under WBC, in the original design, all sub files under the root WBC directory are located on the target MDT same as the root WBC directory.

To obtain the performance improvement in the DNE environment, it can also stripe the directory under WBC that not flushed to MDT when it is growing large enough.

The WBC striping can trigger only on the client side without communications with MDTs expect that get the FID seq from FLD server.
It only needs to determine which MDT targets the large directory will stripe into, can delay the striped directory creation until the flush time.