Lustre Client question
by Vimal Patnaik
Hey folks,
Server version details - Lustre 2.7.19.8
Client version details - Lustre 2.11.0-1 and 2.7.19 (old version) tested on both
Question is...
We have a Lustre client running a primarily compute intensive operation, but which acts over a medium sized data set (~ 80 GB) consisting of a number of files that are ~ 300-500MB big. We're trawling across those files sequentially in a repeated fashion.
We'd like to retain the data set within the Lustre client cache, and have increased this using lctl set_param llite.*.max_cached_mb. However, one observation we've made is that the cache usage appears to top out at ~ 93%, i.e. when configured at the default ~ 70304 MB for this host (140GB mem), the used_mb appears to top out at 65920:
llite.omegad01-ffff88116b38a800.max_cached_mb=
users: 6
max_cached_mb: 70304
used_mb: 65920
unused_mb: 4384
reclaim_count: 0
Likewise, when we up the max to 100000MB, it seems to top out at ~93GB ish (as in we see the used_mb fix, and an increase in network traffic on the Lustre port back to the lustre server).
I'm wondering whether that is expected, and whether there's any configuration option possible to max used of that remaining portion of the cache?
Thanks
Vimal
Vimal Patnaik
Tyler Capital
15 St. Botolph Street
London, EC3A 7DT
Phone: +44 (0)20 7663 3754
Email: VPatnaik(a)tylercapital.co.uk
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