[LU-16757] Allow max_cached_mb to be set as a percentage of system ram

• Type: Improvement
• Resolution: Duplicate
• Priority: Minor
• Affects Version/s: Lustre 2.15.2
• Labels: lug23dd
• Assignee: Patrick Farrell
• Reporter: James Beal

Description

When lustre clients have differing amounts of memory then setting the max_cached_mb  to an absolute number which is the same on all nodes is not likely to provide optimum results. Given vendors like to set this value and place it in the configuration log then allowing max_cached_mb to be a percentage and having the client caculate the exact value to use would be a useability win.

 

We currently do this at Sanger using a ansible templated tuning script:

 

 

{% if adjust_lustre_cache %} {% for key, value in lustre_cache.items() %}

echo We will set the lustre filesystem cache for {{ key }} to {{  (ansible_memtotal_mb * value / 100 )| int }}
lctl set_param llite.{{key*.max_cached_mb={{  (ansible_memtotal_mb * value / 100 )| int }} || true

{% endfor %} {% endif %}

Issue Links

• duplicates: LU-17030 allow setting max_cached_mb with %