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Feature #3462

client: Add null-io debug options to client for testing

Added by Sam Lang over 11 years ago. Updated over 7 years ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
Testing
Target version:
-
% Done:

0%

Source:
Tags:
Backport:
Reviewed:
Affected Versions:
Component(FS):
Client
Labels (FS):
Pull request ID:

Description

When testing metadata behavior and performance (interaction between mds and client), in most cases we don't care about the data, and can avoid the overhead of writing/reading the data to the osds (or caching it at the client).

This is a proposal to add two options to the ceph config:

The first: client null io = true would skip sending I/O requests to the osds from the client (Client doesn't invoke filer->write_trunc and ObjecterWriteback doesn't invoke objecter->write_trunc), instead just completes the I/O request as if the request had been sent.

The second, client null data = true bypasses the client cache entirely (skips the objectcacher->file_write in Client::_write).

An alternative to using config options could be to define a path (/.ceph_null_io/) that would do the above whenever any file rooted at that path was accessed. This would allow us to test metadata behavior and performance on deployments without twiddling the config.

History

#1 Updated by Loïc Dachary over 9 years ago

  • Project changed from Ceph to CephFS

#2 Updated by Greg Farnum over 7 years ago

  • Category set to Testing
  • Component(FS) Client added

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