[LU-3087] File layout change does not generate a changelog record

• Status: Resolved
• Project: Lustre
• Fix Version/s: Lustre 2.4.0
• Type: Bug
• Priority: Minor
• Reporter: CEA
• Assignee: Jinshan Xiong (Inactive)
• Resolution: Fixed
• Severity: 3

Description

When a file layout is created or changed no changelog record is generated.
We propose to add a CL_LAYOUT event.
First use case seen are:

• file created
• layout allocated after file created with LOV_DELAY_CREATE
• layout swap (1 event per file)

Comments

[jacques-charles lafoucriere]

We will propose a patch

[Peter Jones]

Jinshan

I think that you will be the natural person to review this patch when it has been supplied

Peter

[Alex Zhuravlev]

shouldn't the even for xattr change be enough?

[jacques-charles lafoucriere]

The xattr event can be used but it comes from the implementation of lovea and the way it is written on disk. We think a CL_LAYOUT event which matches the "functional" change is better.

[Alex Zhuravlev]

strictly speaking, there is no notion of layout in MDD... MDD isn't even aware always of layout change.

[Henri Doreau (Inactive)]

Additionally, changelog readers (lustre_rsync or robinhood, typically) may react differently to setxattr and layout changes. This was rather in favor of adding a CL_LAYOUT event.

[Alex Zhuravlev]

setxattr(LOVEA) is changing layout by definition, no?

[jacques-charles lafoucriere]

yes but it comes from the way lovea is implemented in lustre, this is side effect of implementation not a goal

[Alex Zhuravlev]

speaking of goals.. I'd rather say there should be no notion of layout on the server (MDS) - the less details to take care about, the better scalability.

[Henri Doreau (Inactive)]

Here's a patch to address the issue: http://review.whamcloud.com/5966

[Peter Jones]

Landed for 2.4