[LUDOC-410] document lctl get_param for changelog size

• Status: Open
• Project: Lustre Documentation
• Type: Improvement
• Priority: Minor
• Reporter: Scott Nolin
• Assignee: Lustre Manual Triage
• Resolution: Unresolved
• Epic/Theme: changelog

Description

The latest manual discusses displaying changelog user information in

12.1.2.5. Displaying the Changelog Index and Registered Users

mdd.*.changelog_size is also important to document, since unconsumed changelogs can cause problems.

This should also include the UNITS that this changelog size is reporting. It's a number, what does that number mean? This is a pet peeve of mine with various lustre stats and numbers from lctl. Some give an xml-ish output with units, others give a number. Chaos! If units aren't included, let's document them.

 

Issue Links

• is related to: LU-7156 Provide size of changelogs

Comments

[Oscar Santos]

To date I don't believe this request has been fulfilled.  So, what is the UNITS returned by "changelog_size" and what is the max value that would lend to the incursion of error messages such as:

there are no more free slots in catalog 

[Andreas Dilger]

The units of "changelog_size" are in bytes. You can use "lctl get_param mdd.*.changelog_users" to get this in "records" units:

mdd.myth-MDT0000.changelog_users=
current index: 75982977
ID    index
cl2   66834025

[Andreas Dilger]

The "changelog_size" parameter was added in patch http://review.whamcloud.com/16416 "LU-7156 mdd: add changelog_size to procfs".